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Diffstat (limited to 'src/runtime/mprof.go')
| -rw-r--r-- | src/runtime/mprof.go | 1283 |
1 files changed, 1283 insertions, 0 deletions
diff --git a/src/runtime/mprof.go b/src/runtime/mprof.go new file mode 100644 index 0000000..99a67b9 --- /dev/null +++ b/src/runtime/mprof.go @@ -0,0 +1,1283 @@ +// Copyright 2009 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Malloc profiling. +// Patterned after tcmalloc's algorithms; shorter code. + +package runtime + +import ( + "internal/abi" + "runtime/internal/atomic" + "unsafe" +) + +// NOTE(rsc): Everything here could use cas if contention became an issue. +var ( + // profInsertLock protects changes to the start of all *bucket linked lists + profInsertLock mutex + // profBlockLock protects the contents of every blockRecord struct + profBlockLock mutex + // profMemActiveLock protects the active field of every memRecord struct + profMemActiveLock mutex + // profMemFutureLock is a set of locks that protect the respective elements + // of the future array of every memRecord struct + profMemFutureLock [len(memRecord{}.future)]mutex +) + +// All memory allocations are local and do not escape outside of the profiler. +// The profiler is forbidden from referring to garbage-collected memory. + +const ( + // profile types + memProfile bucketType = 1 + iota + blockProfile + mutexProfile + + // size of bucket hash table + buckHashSize = 179999 + + // max depth of stack to record in bucket + maxStack = 32 +) + +type bucketType int + +// A bucket holds per-call-stack profiling information. +// The representation is a bit sleazy, inherited from C. +// This struct defines the bucket header. It is followed in +// memory by the stack words and then the actual record +// data, either a memRecord or a blockRecord. +// +// Per-call-stack profiling information. +// Lookup by hashing call stack into a linked-list hash table. +// +// None of the fields in this bucket header are modified after +// creation, including its next and allnext links. +// +// No heap pointers. +// +//go:notinheap +type bucket struct { + next *bucket + allnext *bucket + typ bucketType // memBucket or blockBucket (includes mutexProfile) + hash uintptr + size uintptr + nstk uintptr +} + +// A memRecord is the bucket data for a bucket of type memProfile, +// part of the memory profile. +type memRecord struct { + // The following complex 3-stage scheme of stats accumulation + // is required to obtain a consistent picture of mallocs and frees + // for some point in time. + // The problem is that mallocs come in real time, while frees + // come only after a GC during concurrent sweeping. So if we would + // naively count them, we would get a skew toward mallocs. + // + // Hence, we delay information to get consistent snapshots as + // of mark termination. Allocations count toward the next mark + // termination's snapshot, while sweep frees count toward the + // previous mark termination's snapshot: + // + // MT MT MT MT + // .·| .·| .·| .·| + // .·˙ | .·˙ | .·˙ | .·˙ | + // .·˙ | .·˙ | .·˙ | .·˙ | + // .·˙ |.·˙ |.·˙ |.·˙ | + // + // alloc → ▲ ← free + // ┠┅┅┅┅┅┅┅┅┅┅┅P + // C+2 → C+1 → C + // + // alloc → ▲ ← free + // ┠┅┅┅┅┅┅┅┅┅┅┅P + // C+2 → C+1 → C + // + // Since we can't publish a consistent snapshot until all of + // the sweep frees are accounted for, we wait until the next + // mark termination ("MT" above) to publish the previous mark + // termination's snapshot ("P" above). To do this, allocation + // and free events are accounted to *future* heap profile + // cycles ("C+n" above) and we only publish a cycle once all + // of the events from that cycle must be done. Specifically: + // + // Mallocs are accounted to cycle C+2. + // Explicit frees are accounted to cycle C+2. + // GC frees (done during sweeping) are accounted to cycle C+1. + // + // After mark termination, we increment the global heap + // profile cycle counter and accumulate the stats from cycle C + // into the active profile. + + // active is the currently published profile. A profiling + // cycle can be accumulated into active once its complete. + active memRecordCycle + + // future records the profile events we're counting for cycles + // that have not yet been published. This is ring buffer + // indexed by the global heap profile cycle C and stores + // cycles C, C+1, and C+2. Unlike active, these counts are + // only for a single cycle; they are not cumulative across + // cycles. + // + // We store cycle C here because there's a window between when + // C becomes the active cycle and when we've flushed it to + // active. + future [3]memRecordCycle +} + +// memRecordCycle +type memRecordCycle struct { + allocs, frees uintptr + alloc_bytes, free_bytes uintptr +} + +// add accumulates b into a. It does not zero b. +func (a *memRecordCycle) add(b *memRecordCycle) { + a.allocs += b.allocs + a.frees += b.frees + a.alloc_bytes += b.alloc_bytes + a.free_bytes += b.free_bytes +} + +// A blockRecord is the bucket data for a bucket of type blockProfile, +// which is used in blocking and mutex profiles. +type blockRecord struct { + count float64 + cycles int64 +} + +var ( + mbuckets atomic.UnsafePointer // *bucket, memory profile buckets + bbuckets atomic.UnsafePointer // *bucket, blocking profile buckets + xbuckets atomic.UnsafePointer // *bucket, mutex profile buckets + buckhash atomic.UnsafePointer // *buckhashArray + + mProfCycle mProfCycleHolder +) + +type buckhashArray [buckHashSize]atomic.UnsafePointer // *bucket + +const mProfCycleWrap = uint32(len(memRecord{}.future)) * (2 << 24) + +// mProfCycleHolder holds the global heap profile cycle number (wrapped at +// mProfCycleWrap, stored starting at bit 1), and a flag (stored at bit 0) to +// indicate whether future[cycle] in all buckets has been queued to flush into +// the active profile. +type mProfCycleHolder struct { + value atomic.Uint32 +} + +// read returns the current cycle count. +func (c *mProfCycleHolder) read() (cycle uint32) { + v := c.value.Load() + cycle = v >> 1 + return cycle +} + +// setFlushed sets the flushed flag. It returns the current cycle count and the +// previous value of the flushed flag. +func (c *mProfCycleHolder) setFlushed() (cycle uint32, alreadyFlushed bool) { + for { + prev := c.value.Load() + cycle = prev >> 1 + alreadyFlushed = (prev & 0x1) != 0 + next := prev | 0x1 + if c.value.CompareAndSwap(prev, next) { + return cycle, alreadyFlushed + } + } +} + +// increment increases the cycle count by one, wrapping the value at +// mProfCycleWrap. It clears the flushed flag. +func (c *mProfCycleHolder) increment() { + // We explicitly wrap mProfCycle rather than depending on + // uint wraparound because the memRecord.future ring does not + // itself wrap at a power of two. + for { + prev := c.value.Load() + cycle := prev >> 1 + cycle = (cycle + 1) % mProfCycleWrap + next := cycle << 1 + if c.value.CompareAndSwap(prev, next) { + break + } + } +} + +// newBucket allocates a bucket with the given type and number of stack entries. +func newBucket(typ bucketType, nstk int) *bucket { + size := unsafe.Sizeof(bucket{}) + uintptr(nstk)*unsafe.Sizeof(uintptr(0)) + switch typ { + default: + throw("invalid profile bucket type") + case memProfile: + size += unsafe.Sizeof(memRecord{}) + case blockProfile, mutexProfile: + size += unsafe.Sizeof(blockRecord{}) + } + + b := (*bucket)(persistentalloc(size, 0, &memstats.buckhash_sys)) + b.typ = typ + b.nstk = uintptr(nstk) + return b +} + +// stk returns the slice in b holding the stack. +func (b *bucket) stk() []uintptr { + stk := (*[maxStack]uintptr)(add(unsafe.Pointer(b), unsafe.Sizeof(*b))) + return stk[:b.nstk:b.nstk] +} + +// mp returns the memRecord associated with the memProfile bucket b. +func (b *bucket) mp() *memRecord { + if b.typ != memProfile { + throw("bad use of bucket.mp") + } + data := add(unsafe.Pointer(b), unsafe.Sizeof(*b)+b.nstk*unsafe.Sizeof(uintptr(0))) + return (*memRecord)(data) +} + +// bp returns the blockRecord associated with the blockProfile bucket b. +func (b *bucket) bp() *blockRecord { + if b.typ != blockProfile && b.typ != mutexProfile { + throw("bad use of bucket.bp") + } + data := add(unsafe.Pointer(b), unsafe.Sizeof(*b)+b.nstk*unsafe.Sizeof(uintptr(0))) + return (*blockRecord)(data) +} + +// Return the bucket for stk[0:nstk], allocating new bucket if needed. +func stkbucket(typ bucketType, size uintptr, stk []uintptr, alloc bool) *bucket { + bh := (*buckhashArray)(buckhash.Load()) + if bh == nil { + lock(&profInsertLock) + // check again under the lock + bh = (*buckhashArray)(buckhash.Load()) + if bh == nil { + bh = (*buckhashArray)(sysAlloc(unsafe.Sizeof(buckhashArray{}), &memstats.buckhash_sys)) + if bh == nil { + throw("runtime: cannot allocate memory") + } + buckhash.StoreNoWB(unsafe.Pointer(bh)) + } + unlock(&profInsertLock) + } + + // Hash stack. + var h uintptr + for _, pc := range stk { + h += pc + h += h << 10 + h ^= h >> 6 + } + // hash in size + h += size + h += h << 10 + h ^= h >> 6 + // finalize + h += h << 3 + h ^= h >> 11 + + i := int(h % buckHashSize) + // first check optimistically, without the lock + for b := (*bucket)(bh[i].Load()); b != nil; b = b.next { + if b.typ == typ && b.hash == h && b.size == size && eqslice(b.stk(), stk) { + return b + } + } + + if !alloc { + return nil + } + + lock(&profInsertLock) + // check again under the insertion lock + for b := (*bucket)(bh[i].Load()); b != nil; b = b.next { + if b.typ == typ && b.hash == h && b.size == size && eqslice(b.stk(), stk) { + unlock(&profInsertLock) + return b + } + } + + // Create new bucket. + b := newBucket(typ, len(stk)) + copy(b.stk(), stk) + b.hash = h + b.size = size + + var allnext *atomic.UnsafePointer + if typ == memProfile { + allnext = &mbuckets + } else if typ == mutexProfile { + allnext = &xbuckets + } else { + allnext = &bbuckets + } + + b.next = (*bucket)(bh[i].Load()) + b.allnext = (*bucket)(allnext.Load()) + + bh[i].StoreNoWB(unsafe.Pointer(b)) + allnext.StoreNoWB(unsafe.Pointer(b)) + + unlock(&profInsertLock) + return b +} + +func eqslice(x, y []uintptr) bool { + if len(x) != len(y) { + return false + } + for i, xi := range x { + if xi != y[i] { + return false + } + } + return true +} + +// mProf_NextCycle publishes the next heap profile cycle and creates a +// fresh heap profile cycle. This operation is fast and can be done +// during STW. The caller must call mProf_Flush before calling +// mProf_NextCycle again. +// +// This is called by mark termination during STW so allocations and +// frees after the world is started again count towards a new heap +// profiling cycle. +func mProf_NextCycle() { + mProfCycle.increment() +} + +// mProf_Flush flushes the events from the current heap profiling +// cycle into the active profile. After this it is safe to start a new +// heap profiling cycle with mProf_NextCycle. +// +// This is called by GC after mark termination starts the world. In +// contrast with mProf_NextCycle, this is somewhat expensive, but safe +// to do concurrently. +func mProf_Flush() { + cycle, alreadyFlushed := mProfCycle.setFlushed() + if alreadyFlushed { + return + } + + index := cycle % uint32(len(memRecord{}.future)) + lock(&profMemActiveLock) + lock(&profMemFutureLock[index]) + mProf_FlushLocked(index) + unlock(&profMemFutureLock[index]) + unlock(&profMemActiveLock) +} + +// mProf_FlushLocked flushes the events from the heap profiling cycle at index +// into the active profile. The caller must hold the lock for the active profile +// (profMemActiveLock) and for the profiling cycle at index +// (profMemFutureLock[index]). +func mProf_FlushLocked(index uint32) { + assertLockHeld(&profMemActiveLock) + assertLockHeld(&profMemFutureLock[index]) + head := (*bucket)(mbuckets.Load()) + for b := head; b != nil; b = b.allnext { + mp := b.mp() + + // Flush cycle C into the published profile and clear + // it for reuse. + mpc := &mp.future[index] + mp.active.add(mpc) + *mpc = memRecordCycle{} + } +} + +// mProf_PostSweep records that all sweep frees for this GC cycle have +// completed. This has the effect of publishing the heap profile +// snapshot as of the last mark termination without advancing the heap +// profile cycle. +func mProf_PostSweep() { + // Flush cycle C+1 to the active profile so everything as of + // the last mark termination becomes visible. *Don't* advance + // the cycle, since we're still accumulating allocs in cycle + // C+2, which have to become C+1 in the next mark termination + // and so on. + cycle := mProfCycle.read() + 1 + + index := cycle % uint32(len(memRecord{}.future)) + lock(&profMemActiveLock) + lock(&profMemFutureLock[index]) + mProf_FlushLocked(index) + unlock(&profMemFutureLock[index]) + unlock(&profMemActiveLock) +} + +// Called by malloc to record a profiled block. +func mProf_Malloc(p unsafe.Pointer, size uintptr) { + var stk [maxStack]uintptr + nstk := callers(4, stk[:]) + + index := (mProfCycle.read() + 2) % uint32(len(memRecord{}.future)) + + b := stkbucket(memProfile, size, stk[:nstk], true) + mp := b.mp() + mpc := &mp.future[index] + + lock(&profMemFutureLock[index]) + mpc.allocs++ + mpc.alloc_bytes += size + unlock(&profMemFutureLock[index]) + + // Setprofilebucket locks a bunch of other mutexes, so we call it outside of + // the profiler locks. This reduces potential contention and chances of + // deadlocks. Since the object must be alive during the call to + // mProf_Malloc, it's fine to do this non-atomically. + systemstack(func() { + setprofilebucket(p, b) + }) +} + +// Called when freeing a profiled block. +func mProf_Free(b *bucket, size uintptr) { + index := (mProfCycle.read() + 1) % uint32(len(memRecord{}.future)) + + mp := b.mp() + mpc := &mp.future[index] + + lock(&profMemFutureLock[index]) + mpc.frees++ + mpc.free_bytes += size + unlock(&profMemFutureLock[index]) +} + +var blockprofilerate uint64 // in CPU ticks + +// SetBlockProfileRate controls the fraction of goroutine blocking events +// that are reported in the blocking profile. The profiler aims to sample +// an average of one blocking event per rate nanoseconds spent blocked. +// +// To include every blocking event in the profile, pass rate = 1. +// To turn off profiling entirely, pass rate <= 0. +func SetBlockProfileRate(rate int) { + var r int64 + if rate <= 0 { + r = 0 // disable profiling + } else if rate == 1 { + r = 1 // profile everything + } else { + // convert ns to cycles, use float64 to prevent overflow during multiplication + r = int64(float64(rate) * float64(tickspersecond()) / (1000 * 1000 * 1000)) + if r == 0 { + r = 1 + } + } + + atomic.Store64(&blockprofilerate, uint64(r)) +} + +func blockevent(cycles int64, skip int) { + if cycles <= 0 { + cycles = 1 + } + + rate := int64(atomic.Load64(&blockprofilerate)) + if blocksampled(cycles, rate) { + saveblockevent(cycles, rate, skip+1, blockProfile) + } +} + +// blocksampled returns true for all events where cycles >= rate. Shorter +// events have a cycles/rate random chance of returning true. +func blocksampled(cycles, rate int64) bool { + if rate <= 0 || (rate > cycles && int64(fastrand())%rate > cycles) { + return false + } + return true +} + +func saveblockevent(cycles, rate int64, skip int, which bucketType) { + gp := getg() + var nstk int + var stk [maxStack]uintptr + if gp.m.curg == nil || gp.m.curg == gp { + nstk = callers(skip, stk[:]) + } else { + nstk = gcallers(gp.m.curg, skip, stk[:]) + } + b := stkbucket(which, 0, stk[:nstk], true) + bp := b.bp() + + lock(&profBlockLock) + if which == blockProfile && cycles < rate { + // Remove sampling bias, see discussion on http://golang.org/cl/299991. + bp.count += float64(rate) / float64(cycles) + bp.cycles += rate + } else { + bp.count++ + bp.cycles += cycles + } + unlock(&profBlockLock) +} + +var mutexprofilerate uint64 // fraction sampled + +// SetMutexProfileFraction controls the fraction of mutex contention events +// that are reported in the mutex profile. On average 1/rate events are +// reported. The previous rate is returned. +// +// To turn off profiling entirely, pass rate 0. +// To just read the current rate, pass rate < 0. +// (For n>1 the details of sampling may change.) +func SetMutexProfileFraction(rate int) int { + if rate < 0 { + return int(mutexprofilerate) + } + old := mutexprofilerate + atomic.Store64(&mutexprofilerate, uint64(rate)) + return int(old) +} + +//go:linkname mutexevent sync.event +func mutexevent(cycles int64, skip int) { + if cycles < 0 { + cycles = 0 + } + rate := int64(atomic.Load64(&mutexprofilerate)) + // TODO(pjw): measure impact of always calling fastrand vs using something + // like malloc.go:nextSample() + if rate > 0 && int64(fastrand())%rate == 0 { + saveblockevent(cycles, rate, skip+1, mutexProfile) + } +} + +// Go interface to profile data. + +// A StackRecord describes a single execution stack. +type StackRecord struct { + Stack0 [32]uintptr // stack trace for this record; ends at first 0 entry +} + +// Stack returns the stack trace associated with the record, +// a prefix of r.Stack0. +func (r *StackRecord) Stack() []uintptr { + for i, v := range r.Stack0 { + if v == 0 { + return r.Stack0[0:i] + } + } + return r.Stack0[0:] +} + +// MemProfileRate controls the fraction of memory allocations +// that are recorded and reported in the memory profile. +// The profiler aims to sample an average of +// one allocation per MemProfileRate bytes allocated. +// +// To include every allocated block in the profile, set MemProfileRate to 1. +// To turn off profiling entirely, set MemProfileRate to 0. +// +// The tools that process the memory profiles assume that the +// profile rate is constant across the lifetime of the program +// and equal to the current value. Programs that change the +// memory profiling rate should do so just once, as early as +// possible in the execution of the program (for example, +// at the beginning of main). +var MemProfileRate int = defaultMemProfileRate(512 * 1024) + +// defaultMemProfileRate returns 0 if disableMemoryProfiling is set. +// It exists primarily for the godoc rendering of MemProfileRate +// above. +func defaultMemProfileRate(v int) int { + if disableMemoryProfiling { + return 0 + } + return v +} + +// disableMemoryProfiling is set by the linker if runtime.MemProfile +// is not used and the link type guarantees nobody else could use it +// elsewhere. +var disableMemoryProfiling bool + +// A MemProfileRecord describes the live objects allocated +// by a particular call sequence (stack trace). +type MemProfileRecord struct { + AllocBytes, FreeBytes int64 // number of bytes allocated, freed + AllocObjects, FreeObjects int64 // number of objects allocated, freed + Stack0 [32]uintptr // stack trace for this record; ends at first 0 entry +} + +// InUseBytes returns the number of bytes in use (AllocBytes - FreeBytes). +func (r *MemProfileRecord) InUseBytes() int64 { return r.AllocBytes - r.FreeBytes } + +// InUseObjects returns the number of objects in use (AllocObjects - FreeObjects). +func (r *MemProfileRecord) InUseObjects() int64 { + return r.AllocObjects - r.FreeObjects +} + +// Stack returns the stack trace associated with the record, +// a prefix of r.Stack0. +func (r *MemProfileRecord) Stack() []uintptr { + for i, v := range r.Stack0 { + if v == 0 { + return r.Stack0[0:i] + } + } + return r.Stack0[0:] +} + +// MemProfile returns a profile of memory allocated and freed per allocation +// site. +// +// MemProfile returns n, the number of records in the current memory profile. +// If len(p) >= n, MemProfile copies the profile into p and returns n, true. +// If len(p) < n, MemProfile does not change p and returns n, false. +// +// If inuseZero is true, the profile includes allocation records +// where r.AllocBytes > 0 but r.AllocBytes == r.FreeBytes. +// These are sites where memory was allocated, but it has all +// been released back to the runtime. +// +// The returned profile may be up to two garbage collection cycles old. +// This is to avoid skewing the profile toward allocations; because +// allocations happen in real time but frees are delayed until the garbage +// collector performs sweeping, the profile only accounts for allocations +// that have had a chance to be freed by the garbage collector. +// +// Most clients should use the runtime/pprof package or +// the testing package's -test.memprofile flag instead +// of calling MemProfile directly. +func MemProfile(p []MemProfileRecord, inuseZero bool) (n int, ok bool) { + cycle := mProfCycle.read() + // If we're between mProf_NextCycle and mProf_Flush, take care + // of flushing to the active profile so we only have to look + // at the active profile below. + index := cycle % uint32(len(memRecord{}.future)) + lock(&profMemActiveLock) + lock(&profMemFutureLock[index]) + mProf_FlushLocked(index) + unlock(&profMemFutureLock[index]) + clear := true + head := (*bucket)(mbuckets.Load()) + for b := head; b != nil; b = b.allnext { + mp := b.mp() + if inuseZero || mp.active.alloc_bytes != mp.active.free_bytes { + n++ + } + if mp.active.allocs != 0 || mp.active.frees != 0 { + clear = false + } + } + if clear { + // Absolutely no data, suggesting that a garbage collection + // has not yet happened. In order to allow profiling when + // garbage collection is disabled from the beginning of execution, + // accumulate all of the cycles, and recount buckets. + n = 0 + for b := head; b != nil; b = b.allnext { + mp := b.mp() + for c := range mp.future { + lock(&profMemFutureLock[c]) + mp.active.add(&mp.future[c]) + mp.future[c] = memRecordCycle{} + unlock(&profMemFutureLock[c]) + } + if inuseZero || mp.active.alloc_bytes != mp.active.free_bytes { + n++ + } + } + } + if n <= len(p) { + ok = true + idx := 0 + for b := head; b != nil; b = b.allnext { + mp := b.mp() + if inuseZero || mp.active.alloc_bytes != mp.active.free_bytes { + record(&p[idx], b) + idx++ + } + } + } + unlock(&profMemActiveLock) + return +} + +// Write b's data to r. +func record(r *MemProfileRecord, b *bucket) { + mp := b.mp() + r.AllocBytes = int64(mp.active.alloc_bytes) + r.FreeBytes = int64(mp.active.free_bytes) + r.AllocObjects = int64(mp.active.allocs) + r.FreeObjects = int64(mp.active.frees) + if raceenabled { + racewriterangepc(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0), getcallerpc(), abi.FuncPCABIInternal(MemProfile)) + } + if msanenabled { + msanwrite(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0)) + } + if asanenabled { + asanwrite(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0)) + } + copy(r.Stack0[:], b.stk()) + for i := int(b.nstk); i < len(r.Stack0); i++ { + r.Stack0[i] = 0 + } +} + +func iterate_memprof(fn func(*bucket, uintptr, *uintptr, uintptr, uintptr, uintptr)) { + lock(&profMemActiveLock) + head := (*bucket)(mbuckets.Load()) + for b := head; b != nil; b = b.allnext { + mp := b.mp() + fn(b, b.nstk, &b.stk()[0], b.size, mp.active.allocs, mp.active.frees) + } + unlock(&profMemActiveLock) +} + +// BlockProfileRecord describes blocking events originated +// at a particular call sequence (stack trace). +type BlockProfileRecord struct { + Count int64 + Cycles int64 + StackRecord +} + +// BlockProfile returns n, the number of records in the current blocking profile. +// If len(p) >= n, BlockProfile copies the profile into p and returns n, true. +// If len(p) < n, BlockProfile does not change p and returns n, false. +// +// Most clients should use the runtime/pprof package or +// the testing package's -test.blockprofile flag instead +// of calling BlockProfile directly. +func BlockProfile(p []BlockProfileRecord) (n int, ok bool) { + lock(&profBlockLock) + head := (*bucket)(bbuckets.Load()) + for b := head; b != nil; b = b.allnext { + n++ + } + if n <= len(p) { + ok = true + for b := head; b != nil; b = b.allnext { + bp := b.bp() + r := &p[0] + r.Count = int64(bp.count) + // Prevent callers from having to worry about division by zero errors. + // See discussion on http://golang.org/cl/299991. + if r.Count == 0 { + r.Count = 1 + } + r.Cycles = bp.cycles + if raceenabled { + racewriterangepc(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0), getcallerpc(), abi.FuncPCABIInternal(BlockProfile)) + } + if msanenabled { + msanwrite(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0)) + } + if asanenabled { + asanwrite(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0)) + } + i := copy(r.Stack0[:], b.stk()) + for ; i < len(r.Stack0); i++ { + r.Stack0[i] = 0 + } + p = p[1:] + } + } + unlock(&profBlockLock) + return +} + +// MutexProfile returns n, the number of records in the current mutex profile. +// If len(p) >= n, MutexProfile copies the profile into p and returns n, true. +// Otherwise, MutexProfile does not change p, and returns n, false. +// +// Most clients should use the runtime/pprof package +// instead of calling MutexProfile directly. +func MutexProfile(p []BlockProfileRecord) (n int, ok bool) { + lock(&profBlockLock) + head := (*bucket)(xbuckets.Load()) + for b := head; b != nil; b = b.allnext { + n++ + } + if n <= len(p) { + ok = true + for b := head; b != nil; b = b.allnext { + bp := b.bp() + r := &p[0] + r.Count = int64(bp.count) + r.Cycles = bp.cycles + i := copy(r.Stack0[:], b.stk()) + for ; i < len(r.Stack0); i++ { + r.Stack0[i] = 0 + } + p = p[1:] + } + } + unlock(&profBlockLock) + return +} + +// ThreadCreateProfile returns n, the number of records in the thread creation profile. +// If len(p) >= n, ThreadCreateProfile copies the profile into p and returns n, true. +// If len(p) < n, ThreadCreateProfile does not change p and returns n, false. +// +// Most clients should use the runtime/pprof package instead +// of calling ThreadCreateProfile directly. +func ThreadCreateProfile(p []StackRecord) (n int, ok bool) { + first := (*m)(atomic.Loadp(unsafe.Pointer(&allm))) + for mp := first; mp != nil; mp = mp.alllink { + n++ + } + if n <= len(p) { + ok = true + i := 0 + for mp := first; mp != nil; mp = mp.alllink { + p[i].Stack0 = mp.createstack + i++ + } + } + return +} + +//go:linkname runtime_goroutineProfileWithLabels runtime/pprof.runtime_goroutineProfileWithLabels +func runtime_goroutineProfileWithLabels(p []StackRecord, labels []unsafe.Pointer) (n int, ok bool) { + return goroutineProfileWithLabels(p, labels) +} + +const go119ConcurrentGoroutineProfile = true + +// labels may be nil. If labels is non-nil, it must have the same length as p. +func goroutineProfileWithLabels(p []StackRecord, labels []unsafe.Pointer) (n int, ok bool) { + if labels != nil && len(labels) != len(p) { + labels = nil + } + + if go119ConcurrentGoroutineProfile { + return goroutineProfileWithLabelsConcurrent(p, labels) + } + return goroutineProfileWithLabelsSync(p, labels) +} + +var goroutineProfile = struct { + sema uint32 + active bool + offset atomic.Int64 + records []StackRecord + labels []unsafe.Pointer +}{ + sema: 1, +} + +// goroutineProfileState indicates the status of a goroutine's stack for the +// current in-progress goroutine profile. Goroutines' stacks are initially +// "Absent" from the profile, and end up "Satisfied" by the time the profile is +// complete. While a goroutine's stack is being captured, its +// goroutineProfileState will be "InProgress" and it will not be able to run +// until the capture completes and the state moves to "Satisfied". +// +// Some goroutines (the finalizer goroutine, which at various times can be +// either a "system" or a "user" goroutine, and the goroutine that is +// coordinating the profile, any goroutines created during the profile) move +// directly to the "Satisfied" state. +type goroutineProfileState uint32 + +const ( + goroutineProfileAbsent goroutineProfileState = iota + goroutineProfileInProgress + goroutineProfileSatisfied +) + +type goroutineProfileStateHolder atomic.Uint32 + +func (p *goroutineProfileStateHolder) Load() goroutineProfileState { + return goroutineProfileState((*atomic.Uint32)(p).Load()) +} + +func (p *goroutineProfileStateHolder) Store(value goroutineProfileState) { + (*atomic.Uint32)(p).Store(uint32(value)) +} + +func (p *goroutineProfileStateHolder) CompareAndSwap(old, new goroutineProfileState) bool { + return (*atomic.Uint32)(p).CompareAndSwap(uint32(old), uint32(new)) +} + +func goroutineProfileWithLabelsConcurrent(p []StackRecord, labels []unsafe.Pointer) (n int, ok bool) { + semacquire(&goroutineProfile.sema) + + ourg := getg() + + stopTheWorld("profile") + // Using gcount while the world is stopped should give us a consistent view + // of the number of live goroutines, minus the number of goroutines that are + // alive and permanently marked as "system". But to make this count agree + // with what we'd get from isSystemGoroutine, we need special handling for + // goroutines that can vary between user and system to ensure that the count + // doesn't change during the collection. So, check the finalizer goroutine + // in particular. + n = int(gcount()) + if fingRunning { + n++ + } + + if n > len(p) { + // There's not enough space in p to store the whole profile, so (per the + // contract of runtime.GoroutineProfile) we're not allowed to write to p + // at all and must return n, false. + startTheWorld() + semrelease(&goroutineProfile.sema) + return n, false + } + + // Save current goroutine. + sp := getcallersp() + pc := getcallerpc() + systemstack(func() { + saveg(pc, sp, ourg, &p[0]) + }) + ourg.goroutineProfiled.Store(goroutineProfileSatisfied) + goroutineProfile.offset.Store(1) + + // Prepare for all other goroutines to enter the profile. Aside from ourg, + // every goroutine struct in the allgs list has its goroutineProfiled field + // cleared. Any goroutine created from this point on (while + // goroutineProfile.active is set) will start with its goroutineProfiled + // field set to goroutineProfileSatisfied. + goroutineProfile.active = true + goroutineProfile.records = p + goroutineProfile.labels = labels + // The finalizer goroutine needs special handling because it can vary over + // time between being a user goroutine (eligible for this profile) and a + // system goroutine (to be excluded). Pick one before restarting the world. + if fing != nil { + fing.goroutineProfiled.Store(goroutineProfileSatisfied) + if readgstatus(fing) != _Gdead && !isSystemGoroutine(fing, false) { + doRecordGoroutineProfile(fing) + } + } + startTheWorld() + + // Visit each goroutine that existed as of the startTheWorld call above. + // + // New goroutines may not be in this list, but we didn't want to know about + // them anyway. If they do appear in this list (via reusing a dead goroutine + // struct, or racing to launch between the world restarting and us getting + // the list), they will already have their goroutineProfiled field set to + // goroutineProfileSatisfied before their state transitions out of _Gdead. + // + // Any goroutine that the scheduler tries to execute concurrently with this + // call will start by adding itself to the profile (before the act of + // executing can cause any changes in its stack). + forEachGRace(func(gp1 *g) { + tryRecordGoroutineProfile(gp1, Gosched) + }) + + stopTheWorld("profile cleanup") + endOffset := goroutineProfile.offset.Swap(0) + goroutineProfile.active = false + goroutineProfile.records = nil + goroutineProfile.labels = nil + startTheWorld() + + // Restore the invariant that every goroutine struct in allgs has its + // goroutineProfiled field cleared. + forEachGRace(func(gp1 *g) { + gp1.goroutineProfiled.Store(goroutineProfileAbsent) + }) + + if raceenabled { + raceacquire(unsafe.Pointer(&labelSync)) + } + + if n != int(endOffset) { + // It's a big surprise that the number of goroutines changed while we + // were collecting the profile. But probably better to return a + // truncated profile than to crash the whole process. + // + // For instance, needm moves a goroutine out of the _Gdead state and so + // might be able to change the goroutine count without interacting with + // the scheduler. For code like that, the race windows are small and the + // combination of features is uncommon, so it's hard to be (and remain) + // sure we've caught them all. + } + + semrelease(&goroutineProfile.sema) + return n, true +} + +// tryRecordGoroutineProfileWB asserts that write barriers are allowed and calls +// tryRecordGoroutineProfile. +// +//go:yeswritebarrierrec +func tryRecordGoroutineProfileWB(gp1 *g) { + if getg().m.p.ptr() == nil { + throw("no P available, write barriers are forbidden") + } + tryRecordGoroutineProfile(gp1, osyield) +} + +// tryRecordGoroutineProfile ensures that gp1 has the appropriate representation +// in the current goroutine profile: either that it should not be profiled, or +// that a snapshot of its call stack and labels are now in the profile. +func tryRecordGoroutineProfile(gp1 *g, yield func()) { + if readgstatus(gp1) == _Gdead { + // Dead goroutines should not appear in the profile. Goroutines that + // start while profile collection is active will get goroutineProfiled + // set to goroutineProfileSatisfied before transitioning out of _Gdead, + // so here we check _Gdead first. + return + } + if isSystemGoroutine(gp1, true) { + // System goroutines should not appear in the profile. (The finalizer + // goroutine is marked as "already profiled".) + return + } + + for { + prev := gp1.goroutineProfiled.Load() + if prev == goroutineProfileSatisfied { + // This goroutine is already in the profile (or is new since the + // start of collection, so shouldn't appear in the profile). + break + } + if prev == goroutineProfileInProgress { + // Something else is adding gp1 to the goroutine profile right now. + // Give that a moment to finish. + yield() + continue + } + + // While we have gp1.goroutineProfiled set to + // goroutineProfileInProgress, gp1 may appear _Grunnable but will not + // actually be able to run. Disable preemption for ourselves, to make + // sure we finish profiling gp1 right away instead of leaving it stuck + // in this limbo. + mp := acquirem() + if gp1.goroutineProfiled.CompareAndSwap(goroutineProfileAbsent, goroutineProfileInProgress) { + doRecordGoroutineProfile(gp1) + gp1.goroutineProfiled.Store(goroutineProfileSatisfied) + } + releasem(mp) + } +} + +// doRecordGoroutineProfile writes gp1's call stack and labels to an in-progress +// goroutine profile. Preemption is disabled. +// +// This may be called via tryRecordGoroutineProfile in two ways: by the +// goroutine that is coordinating the goroutine profile (running on its own +// stack), or from the scheduler in preparation to execute gp1 (running on the +// system stack). +func doRecordGoroutineProfile(gp1 *g) { + if readgstatus(gp1) == _Grunning { + print("doRecordGoroutineProfile gp1=", gp1.goid, "\n") + throw("cannot read stack of running goroutine") + } + + offset := int(goroutineProfile.offset.Add(1)) - 1 + + if offset >= len(goroutineProfile.records) { + // Should be impossible, but better to return a truncated profile than + // to crash the entire process at this point. Instead, deal with it in + // goroutineProfileWithLabelsConcurrent where we have more context. + return + } + + // saveg calls gentraceback, which may call cgo traceback functions. When + // called from the scheduler, this is on the system stack already so + // traceback.go:cgoContextPCs will avoid calling back into the scheduler. + // + // When called from the goroutine coordinating the profile, we still have + // set gp1.goroutineProfiled to goroutineProfileInProgress and so are still + // preventing it from being truly _Grunnable. So we'll use the system stack + // to avoid schedule delays. + systemstack(func() { saveg(^uintptr(0), ^uintptr(0), gp1, &goroutineProfile.records[offset]) }) + + if goroutineProfile.labels != nil { + goroutineProfile.labels[offset] = gp1.labels + } +} + +func goroutineProfileWithLabelsSync(p []StackRecord, labels []unsafe.Pointer) (n int, ok bool) { + gp := getg() + + isOK := func(gp1 *g) bool { + // Checking isSystemGoroutine here makes GoroutineProfile + // consistent with both NumGoroutine and Stack. + return gp1 != gp && readgstatus(gp1) != _Gdead && !isSystemGoroutine(gp1, false) + } + + stopTheWorld("profile") + + // World is stopped, no locking required. + n = 1 + forEachGRace(func(gp1 *g) { + if isOK(gp1) { + n++ + } + }) + + if n <= len(p) { + ok = true + r, lbl := p, labels + + // Save current goroutine. + sp := getcallersp() + pc := getcallerpc() + systemstack(func() { + saveg(pc, sp, gp, &r[0]) + }) + r = r[1:] + + // If we have a place to put our goroutine labelmap, insert it there. + if labels != nil { + lbl[0] = gp.labels + lbl = lbl[1:] + } + + // Save other goroutines. + forEachGRace(func(gp1 *g) { + if !isOK(gp1) { + return + } + + if len(r) == 0 { + // Should be impossible, but better to return a + // truncated profile than to crash the entire process. + return + } + // saveg calls gentraceback, which may call cgo traceback functions. + // The world is stopped, so it cannot use cgocall (which will be + // blocked at exitsyscall). Do it on the system stack so it won't + // call into the schedular (see traceback.go:cgoContextPCs). + systemstack(func() { saveg(^uintptr(0), ^uintptr(0), gp1, &r[0]) }) + if labels != nil { + lbl[0] = gp1.labels + lbl = lbl[1:] + } + r = r[1:] + }) + } + + if raceenabled { + raceacquire(unsafe.Pointer(&labelSync)) + } + + startTheWorld() + return n, ok +} + +// GoroutineProfile returns n, the number of records in the active goroutine stack profile. +// If len(p) >= n, GoroutineProfile copies the profile into p and returns n, true. +// If len(p) < n, GoroutineProfile does not change p and returns n, false. +// +// Most clients should use the runtime/pprof package instead +// of calling GoroutineProfile directly. +func GoroutineProfile(p []StackRecord) (n int, ok bool) { + + return goroutineProfileWithLabels(p, nil) +} + +func saveg(pc, sp uintptr, gp *g, r *StackRecord) { + n := gentraceback(pc, sp, 0, gp, 0, &r.Stack0[0], len(r.Stack0), nil, nil, 0) + if n < len(r.Stack0) { + r.Stack0[n] = 0 + } +} + +// Stack formats a stack trace of the calling goroutine into buf +// and returns the number of bytes written to buf. +// If all is true, Stack formats stack traces of all other goroutines +// into buf after the trace for the current goroutine. +func Stack(buf []byte, all bool) int { + if all { + stopTheWorld("stack trace") + } + + n := 0 + if len(buf) > 0 { + gp := getg() + sp := getcallersp() + pc := getcallerpc() + systemstack(func() { + g0 := getg() + // Force traceback=1 to override GOTRACEBACK setting, + // so that Stack's results are consistent. + // GOTRACEBACK is only about crash dumps. + g0.m.traceback = 1 + g0.writebuf = buf[0:0:len(buf)] + goroutineheader(gp) + traceback(pc, sp, 0, gp) + if all { + tracebackothers(gp) + } + g0.m.traceback = 0 + n = len(g0.writebuf) + g0.writebuf = nil + }) + } + + if all { + startTheWorld() + } + return n +} + +// Tracing of alloc/free/gc. + +var tracelock mutex + +func tracealloc(p unsafe.Pointer, size uintptr, typ *_type) { + lock(&tracelock) + gp := getg() + gp.m.traceback = 2 + if typ == nil { + print("tracealloc(", p, ", ", hex(size), ")\n") + } else { + print("tracealloc(", p, ", ", hex(size), ", ", typ.string(), ")\n") + } + if gp.m.curg == nil || gp == gp.m.curg { + goroutineheader(gp) + pc := getcallerpc() + sp := getcallersp() + systemstack(func() { + traceback(pc, sp, 0, gp) + }) + } else { + goroutineheader(gp.m.curg) + traceback(^uintptr(0), ^uintptr(0), 0, gp.m.curg) + } + print("\n") + gp.m.traceback = 0 + unlock(&tracelock) +} + +func tracefree(p unsafe.Pointer, size uintptr) { + lock(&tracelock) + gp := getg() + gp.m.traceback = 2 + print("tracefree(", p, ", ", hex(size), ")\n") + goroutineheader(gp) + pc := getcallerpc() + sp := getcallersp() + systemstack(func() { + traceback(pc, sp, 0, gp) + }) + print("\n") + gp.m.traceback = 0 + unlock(&tracelock) +} + +func tracegc() { + lock(&tracelock) + gp := getg() + gp.m.traceback = 2 + print("tracegc()\n") + // running on m->g0 stack; show all non-g0 goroutines + tracebackothers(gp) + print("end tracegc\n") + print("\n") + gp.m.traceback = 0 + unlock(&tracelock) +} |