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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2018-11-07 12:19:29 +0000 |
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| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2018-11-07 12:20:17 +0000 |
| commit | a64a253794ac64cb40befee54db53bde17dd0d49 (patch) | |
| tree | c1024acc5f6e508814b944d99f112259bb28b1be /collectors/apps.plugin/README.md | |
| parent | New upstream version 1.10.0+dfsg (diff) | |
| download | netdata-a64a253794ac64cb40befee54db53bde17dd0d49.tar.xz netdata-a64a253794ac64cb40befee54db53bde17dd0d49.zip | |
New upstream version 1.11.0+dfsgupstream/1.11.0+dfsg
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'collectors/apps.plugin/README.md')
| -rw-r--r-- | collectors/apps.plugin/README.md | 372 |
1 files changed, 372 insertions, 0 deletions
diff --git a/collectors/apps.plugin/README.md b/collectors/apps.plugin/README.md new file mode 100644 index 00000000..05680efe --- /dev/null +++ b/collectors/apps.plugin/README.md @@ -0,0 +1,372 @@ +# apps.plugin + +`apps.plugin` breaks down system resource usage to **processes**, **users** and **user groups**. + +To achieve this task, it iterates through the whole process tree, collecting resource usage information +for every process found running. + +Since netdata needs to present this information in charts and track them through time, +instead of presenting a `top` like list, `apps.plugin` uses a pre-defined list of **process groups** +to which it assigns all running processes. This list is [customizable](apps_groups.conf) and netdata +ships with a good default for most cases (to edit it on your system run `/etc/netdata/edit-config apps_groups.conf`). + +So, `apps.plugin` builds a process tree (much like `ps fax` does in Linux), and groups +processes together (evaluating both child and parent processes) so that the result is always a list with +a predefined set of members (of course, only process groups found running are reported). + +> If you find that `apps.plugin` categorizes standard applications as `other`, we would be +> glad to accept pull requests improving the [defaults](apps_groups.conf) shipped with netdata. + +Unlike traditional process monitoring tools (like `top`), `apps.plugin` is able to account the resource +utilization of exit processes. Their utilization is accounted at their currently running parents. +So, `apps.plugin` is perfectly able to measure the resources used by shell scripts and other processes +that fork/spawn other short lived processes hundreds of times per second. + +## Charts + +`apps.plugin` provides charts for 3 sections: + +1. Per application charts as **Applications** at netdata dashboards +2. Per user charts as **Users** at netdata dashboards +3. Per user group charts as **User Groups** at netdata dashboards + +Each of these sections provides the same number of charts: + +- CPU Utilization + - Total CPU usage + - User / System CPU usage +- Disk I/O + - Physical Reads / Writes + - Logical Reads / Writes + - Open Unique Files (if a file is found open multiple times, it is counted just once) +- Memory + - Real Memory Used (non shared) + - Virtual Memory Allocated + - Minor Page Faults (i.e. memory activity) +- Processes + - Threads Running + - Processes Running + - Pipes Open +- Swap Memory + - Swap Memory Used + - Major Page Faults (i.e. swap activity) +- Network + - Sockets Open + +The above are reported: + +- For **Applications** per [target configured](apps_groups.conf). +- For **Users** per username or UID (when the username is not available). +- For **User Groups** per groupname or GID (when groupname is not available). + +## Performance + +`apps.plugin` is a complex piece of software and has a lot of work to do +We are proud that `apps.plugin` is a lot faster compared to any other similar tool, +while collecting a lot more information for the processes, however the fact is that +this plugin requires more CPU resources than the netdata daemon itself. + +Under Linux, for each process running, `apps.plugin` reads several `/proc` files +per process. Doing this work per-second, especially on hosts with several thousands +of processes, may increase the CPU resources consumed by the plugin. + +In such cases, you many need to lower its data collection frequency. + +To do this, edit `/etc/netdata/netdata.conf` and find this section: + +``` +[plugin:apps] + # update every = 1 + # command options = +``` + +Uncomment the line `update every` and set it to a higher number. If you just set it to ` 2 `, +its CPU resources will be cut in half, and data collection will be once every 2 seconds. + +## Configuration + +The configuration file is `/etc/netdata/apps_groups.conf` (the default is [here](apps_groups.conf)). +To edit it on your system run `/etc/netdata/edit-config apps_groups.conf`. + +The configuration file works accepts multiple lines, each having this format: + +```txt +group: process1 process2 ... +``` + +Each group can be given multiple times, to add more processes to it. + +For the **Applications** section, only groups configured in this file are reported. +All other processes will be reported as `other`. + +For each process given, its whole process tree will be grouped, not just the process matched. +The plugin will include both parents and children. + +The process names are the ones returned by: + + - `ps -e` or `cat /proc/PID/stat` + - in case of substring mode (see below): `/proc/PID/cmdline` + +To add process names with spaces, enclose them in quotes (single or double) +example: ` 'Plex Media Serv' ` or ` "my other process" `. + +You can add an asterisk ` * ` at the beginning and/or the end of a process: + + - `*name` *suffix* mode: will search for processes ending with `name` (at `/proc/PID/stat`) + - `name*` *prefix* mode: will search for processes beginning with `name` (at `/proc/PID/stat`) + - `*name*` *substring* mode: will search for `name` in the whole command line (at `/proc/PID/cmdline`) + +If you enter even just one *name* (substring), `apps.plugin` will process +`/proc/PID/cmdline` for all processes (of course only once per process: when they are first seen). + +To add processes with single quotes, enclose them in double quotes: ` "process with this ' single quote" ` + +To add processes with double quotes, enclose them in single quotes: ` 'process with this " double quote' ` + +If a group or process name starts with a ` - `, the dimension will be hidden from the chart (cpu chart only). + +If a process starts with a ` + `, debugging will be enabled for it (debugging produces a lot of output - do not enable it in production systems). + +You can add any number of groups. Only the ones found running will affect the charts generated. +However, producing charts with hundreds of dimensions may slow down your web browser. + +The order of the entries in this list is important: the first that matches a process is used, so put important +ones at the top. Processes not matched by any row, will inherit it from their parents or children. + +The order also controls the order of the dimensions on the generated charts (although applications started +after apps.plugin is started, will be appended to the existing list of dimensions the netdata daemon maintains). + +## Permissions + +`apps.plugin` requires additional privileges to collect all the information it needs. +The problem is described in issue #157. + +When netdata is installed, `apps.plugin` is given the capabilities `cap_dac_read_search,cap_sys_ptrace+ep`. +If this fails (i.e. `setcap` fails), `apps.plugin` is setuid to `root`. + +#### linux capabilities in containers + +There are a few cases, like `docker` and `virtuozzo` containers, where `setcap` succeeds, but the capabilities +are silently ignored (in `lxc` containers `setcap` fails). + +In these cases ()`setcap` succeeds but capabilities do not work), you will have to setuid +to root `apps.plugin` by running these commands: + +```sh +chown root:netdata /usr/libexec/netdata/plugins.d/apps.plugin +chmod 4750 /usr/libexec/netdata/plugins.d/apps.plugin +``` + +You will have to run these, every time you update netdata. + +## Security + +`apps.plugin` performs a hard-coded function of building the process tree in memory, +iterating forever, collecting metrics for each running process and sending them to netdata. +This is a one-way communication, from `apps.plugin` to netdata. + +So, since `apps.plugin` cannot be instructed by netdata for the actions it performs, +we think it is pretty safe to allow it have these increased privileges. + +Keep in mind that `apps.plugin` will still run without escalated permissions, +but it will not be able to collect all the information. + +## Application Badges + +You can create badges that you can embed anywhere you like, with URLs like this: + +``` +https://your.netdata.ip:19999/api/v1/badge.svg?chart=apps.processes&dimensions=myapp&value_color=green%3E0%7Cred +``` + +The color expression unescaped is this: `value_color=green>0|red`. + +Here is an example for the process group `sql` at `https://registry.my-netdata.io`: + + + +Netdata is able give you a lot more badges for your app. +Examples below for process group `sql`: + +- CPU usage:  +- Disk Physical Reads  +- Disk Physical Writes  +- Disk Logical Reads  +- Disk Logical Writes  +- Open Files  +- Real Memory  +- Virtual Memory  +- Swap Memory  +- Minor Page Faults  +- Processes  +- Threads  +- Major Faults (swap activity)  +- Open Pipes  +- Open Sockets  + + +For more information about badges check [Generating Badges](../../web/api/badges) + +## Comparison with console tools + +Ssh to a server running netdata and execute this: + +```sh +while true; do ls -l /var/run >/dev/null; done +``` + +In most systems `/var/run` is a `tmpfs` device, so there is nothing that can stop this command +from consuming entirely one of the CPU cores of the machine. + +As we will see below, **none** of the console performance monitoring tools can report that this +command is using 100% CPU. They do report of course that the CPU is busy, but **they fail to +identify the process that consumes so much CPU**. + +Here is what common Linux console monitoring tools report: + +#### top + +`top` reports that `bash` is using just 14%. + +If you check the total system CPU utilization, it says there is no idle CPU at all, but `top` +fails to provide a breakdown of the CPU consumption in the system. The sum of the CPU utilization +of all processes reported by `top`, is 15.6%. + +``` +top - 18:46:28 up 3 days, 20:14, 2 users, load average: 0.22, 0.05, 0.02 +Tasks: 76 total, 2 running, 74 sleeping, 0 stopped, 0 zombie +%Cpu(s): 32.8 us, 65.6 sy, 0.0 ni, 0.0 id, 0.0 wa, 1.3 hi, 0.3 si, 0.0 st +KiB Mem : 1016576 total, 244112 free, 52012 used, 720452 buff/cache +KiB Swap: 0 total, 0 free, 0 used. 753712 avail Mem + + PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND +12789 root 20 0 14980 4180 3020 S 14.0 0.4 0:02.82 bash + 9 root 20 0 0 0 0 S 1.0 0.0 0:22.36 rcuos/0 + 642 netdata 20 0 132024 20112 2660 S 0.3 2.0 14:26.29 netdata +12522 netdata 20 0 9508 2476 1828 S 0.3 0.2 0:02.26 apps.plugin + 1 root 20 0 67196 10216 7500 S 0.0 1.0 0:04.83 systemd + 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd +``` + +#### htop + +Exactly like `top`, `htop` is providing an incomplete breakdown of the system CPU utilization. + +``` + CPU[||||||||||||||||||||||||100.0%] Tasks: 27, 11 thr; 2 running + Mem[||||||||||||||||||||85.4M/993M] Load average: 1.16 0.88 0.90 + Swp[ 0K/0K] Uptime: 3 days, 21:37:03 + + PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command +12789 root 20 0 15104 4484 3208 S 14.0 0.4 10:57.15 -bash + 7024 netdata 20 0 9544 2480 1744 S 0.7 0.2 0:00.88 /usr/libexec/netd + 7009 netdata 20 0 138M 21016 2712 S 0.7 2.1 0:00.89 /usr/sbin/netdata + 7012 netdata 20 0 138M 21016 2712 S 0.0 2.1 0:00.31 /usr/sbin/netdata + 563 root 20 0 308M 202M 202M S 0.0 20.4 1:00.81 /usr/lib/systemd/ + 7019 netdata 20 0 138M 21016 2712 S 0.0 2.1 0:00.14 /usr/sbin/netdata +``` + +#### atop + +`atop` also fails to break down CPU usage. + +``` +ATOP - localhost 2016/12/10 20:11:27 ----------- 10s elapsed +PRC | sys 1.13s | user 0.43s | #proc 75 | #zombie 0 | #exit 5383 | +CPU | sys 67% | user 31% | irq 2% | idle 0% | wait 0% | +CPL | avg1 1.34 | avg5 1.05 | avg15 0.96 | csw 51346 | intr 10508 | +MEM | tot 992.8M | free 211.5M | cache 470.0M | buff 87.2M | slab 164.7M | +SWP | tot 0.0M | free 0.0M | | vmcom 207.6M | vmlim 496.4M | +DSK | vda | busy 0% | read 0 | write 4 | avio 1.50 ms | +NET | transport | tcpi 16 | tcpo 15 | udpi 0 | udpo 0 | +NET | network | ipi 16 | ipo 15 | ipfrw 0 | deliv 16 | +NET | eth0 ---- | pcki 16 | pcko 15 | si 1 Kbps | so 4 Kbps | + + PID SYSCPU USRCPU VGROW RGROW RDDSK WRDSK ST EXC S CPU CMD 1/600 +12789 0.98s 0.40s 0K 0K 0K 336K -- - S 14% bash + 9 0.08s 0.00s 0K 0K 0K 0K -- - S 1% rcuos/0 + 7024 0.03s 0.00s 0K 0K 0K 0K -- - S 0% apps.plugin + 7009 0.01s 0.01s 0K 0K 0K 4K -- - S 0% netdata +``` + +#### glances + +And the same is true for `glances`. The system runs at 100%, but `glances` reports only 17% +per process utilization. + +Note also, that being a `python` program, `glances` uses 1.6% CPU while it runs. + + +``` +localhost Uptime: 3 days, 21:42:00 + +CPU [100.0%] CPU 100.0% MEM 23.7% SWAP 0.0% LOAD 1-core +MEM [ 23.7%] user: 30.9% total: 993M total: 0 1 min: 1.18 +SWAP [ 0.0%] system: 67.8% used: 236M used: 0 5 min: 1.08 + idle: 0.0% free: 757M free: 0 15 min: 1.00 + +NETWORK Rx/s Tx/s TASKS 75 (90 thr), 1 run, 74 slp, 0 oth +eth0 168b 2Kb +eth1 0b 0b CPU% MEM% PID USER NI S Command +lo 0b 0b 13.5 0.4 12789 root 0 S -bash + 1.6 2.2 7025 root 0 R /usr/bin/python /u +DISK I/O R/s W/s 1.0 0.0 9 root 0 S rcuos/0 +vda1 0 4K 0.3 0.2 7024 netdata 0 S /usr/libexec/netda + 0.3 0.0 7 root 0 S rcu_sched +FILE SYS Used Total 0.3 2.1 7009 netdata 0 S /usr/sbin/netdata +/ (vda1) 1.56G 29.5G 0.0 0.0 17 root 0 S oom_reaper +``` + +#### why this happens? + +All the console tools report usage based on the processes found running *at the moment they +examine the process tree*. So, they see just one `ls` command, which is actually very quick +with minor CPU utilization. But the shell, is spawning hundreds of them, one after another +(much like shell scripts do). + +#### what netdata reports? + +The total CPU utilization of the system: + + +<br/>_**Figure 1**: The system overview section at netdata, just a few seconds after the command was run_ + +And at the applications `apps.plugin` breaks down CPU usage per application: + + +<br/>_**Figure 2**: The Applications section at netdata, just a few seconds after the command was run_ + +So, the `ssh` session is using 95% CPU time. + +Why `ssh`? + +`apps.plugin` groups all processes based on its configuration file +[`/etc/netdata/apps_groups.conf`](apps_groups.conf) +(to edit it on your system run `/etc/netdata/edit-config apps_groups.conf`). +The default configuration has nothing for `bash`, but it has for `sshd`, so netdata accumulates +all ssh sessions to a dimension on the charts, called `ssh`. This includes all the processes in +the process tree of `sshd`, **including the exited children**. + +> Distributions based on `systemd`, provide another way to get cpu utilization per user session +> or service running: control groups, or cgroups, commonly used as part of containers +> `apps.plugin` does not use these mechanisms. The process grouping made by `apps.plugin` works +> on any Linux, `systemd` based or not. + +#### a more technical description of how netdata works + +netdata reads `/proc/<pid>/stat` for all processes, once per second and extracts `utime` and +`stime` (user and system cpu utilization), much like all the console tools do. + +But it [also extracts `cutime` and `cstime`](https://github.com/netdata/netdata/blob/62596cc6b906b1564657510ca9135c08f6d4cdda/src/apps_plugin.c#L636-L642) +that account the user and system time of the exit children of each process. By keeping a map in +memory of the whole process tree, it is capable of assigning the right time to every process, +taking into account all its exited children. + +It is tricky, since a process may be running for 1 hour and once it exits, its parent should not +receive the whole 1 hour of cpu time in just 1 second - you have to subtract the cpu time that has +been reported for it prior to this iteration. + +It is even trickier, because walking through the entire process tree takes some time itself. So, +if you sum the CPU utilization of all processes, you might have more CPU time than the reported +total cpu time of the system. netdata solves this, by adapting the per process cpu utilization to +the total of the system. [Netdata adds charts that document this normalization](https://london.my-netdata.io/default.html#menu_netdata_submenu_apps_plugin). |