// AutoStableStringChars needs to prevent the owner of its chars from being // deduplicated, even if they are held by a different string. gczeal(0); function makeExtensibleStrFrom(str) { var left = str.substr(0, str.length/2); var right = str.substr(str.length/2, str.length); var ropeStr = left + right; return ensureLinearString(ropeStr); } // Make a string to deduplicate to. var original = makeExtensibleStrFrom('{ "phbbbbbbbbbbbbbbttt!!!!??": [1] }\n\n'); // Construct D2 -> D1 -> base var D2 = makeExtensibleStrFrom('{ "phbbbbbbbbbbbbbbttt!!!!??": [1] }'); var D1 = newRope(D2, '\n', {nursery: true}); ensureLinearString(D1); var base = newRope(D1, '\n', {nursery: true}); ensureLinearString(base); // Make an AutoStableStringChars(D2) and do a minor GC within it. (This will do // a major GC, but it'll start out with a minor GC.) `base` would get // deduplicated to `original`, if it weren't for AutoStableStringChars marking // all of D2, D1, and base non-deduplicatable. // The first time JSON.parse runs, it will create several (14 in my test) GC // things before getting to the point where it does an allocation while holding // the chars pointer. Get them out of the way now. JSON.parse(D2); // Cause a minor GC to happen during JSON.parse after AutoStableStringChars // gives up its pointer. schedulegc(1); JSON.parse(D2); // Access `D2` to verify that it is not using the deduplicated chars. print(D2);