- 21 Nov, 2017 1 commit
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Alexey Kozyatinskiy authored
Old instrumentation was designed to collect promise creation stack and promise scheduled stack together. In DevTools for last 6 months we show only creation stack for promises. We got strong support from users for new model. Now we can drop support for scheduled stacks and simplify implementation. New promise instrumentation is straightforward: - we send kDebugPromiseThen when promise is created by .then call, - we send kDebugPromiseCatch when promise is created by .catch call, - we send kDebugWillHandle before chained callback and kDebugDidHandle after chained callback, - and we send separate kDebugAsyncFunctionPromiseCreated for internal promise inside async await function. Advantages: - we reduce amount of captured stacks (we do not capture stack for promise that constructed not by .then or .catch), - we can consider async task related to .then and .catch as one shot since chained callback is executed once, - on V8 side we can implement required instrumentation using only promise hooks, Disadvantage: - see await-promise test, sometimes scheduled stack was useful since we add catch handler in native code, Implementation details: - on kInit promise hook we need to figure out why promise was created. We analyze builtin functions until first user defined function on current stack. If there is kAsyncFunctionPromiseCreate function then we send kDebugAsyncFunctionPromiseCreated event. If there is kPromiseThen or kPromiseCatch then only if this function is bottom builtin function we send corresponded event to inspector. We need it because Promise.all internally calls .then and in this case we have Promise.all and Promise.then on stack at the same time and we do not need to report this internally created promise to inspector. Bug: chromium:778796 Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel Change-Id: I53f47ce8c5c4a9897655c3396c249ea59529ae47 Reviewed-on: https://chromium-review.googlesource.com/765208 Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org> Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org> Reviewed-by: Yang Guo <yangguo@chromium.org> Reviewed-by: Dmitry Gozman <dgozman@chromium.org> Cr-Commit-Position: refs/heads/master@{#49553}
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- 20 Apr, 2017 1 commit
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kozyatinskiy authored
With recent CLs we always store maximum N async stack traces and when we reach limit we drop half of them. Current promise collected event requires creating weak handle: - it takes time, - it consumes memory. Since async task id distribution for promises is uniform (each new promise has last_async_task_id + 1 as an id) our hash map is good enough to handle any amount of async task ids, following time of executing 1 000 000 000 of lookups: - for empty hash map: 1.45 seconds, - for hash map with one entry: 14.95 seconds - 1024 entries: 15.03 seconds - 1024 * 1024 entries: 14.82 seconds - 1024 * 1024 * 1024: 17.9 seconds BUG=v8:6189 R=dgozman@chromium.org,yangguo@chromium.org Review-Url: https://codereview.chromium.org/2819423005 Cr-Commit-Position: refs/heads/master@{#44750}
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