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Update documentation for heap profiler.

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Change-Id: Icf63c40bfeb356bb219a9ba0f8fd215030bc45f0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1531229
Reviewed-by: enne <enne@chromium.org>
Commit-Queue: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#642244}
This commit is contained in:
Erik Chen
2019-03-19 23:15:56 +00:00
committed by Commit Bot
parent 31ff97f136
commit fadc10b465
1 changed files with 14 additions and 26 deletions

40
docs/memory-infra/heap_profiler.md

@ -4,41 +4,29 @@ As of Chrome 48, MemoryInfra supports heap profiling. Chrome will track all live
allocations (calls to new or malloc without a subsequent call to delete or free)
along with sufficient metadata to identify the code that made the allocation.
By default, MemoryInfra traces will not contain heap dumps. Heap profiling must
be enabled via chrome://memory-internals or about://flags.
[TOC]
## How to obtain a heap dump (M66+, Linux, macOS, Windows)
1. Navigate to chrome://flags and search for `memlog`.
2. Choose the process types you want to profile with the `memlog` flag. The
most common setting is `Only Browser`.
3. You can control resolution of sampling with `memlog-sampling-rate`.
By default samples are collected with the average interval of 100KB.
On versions prior Chrome 75 you can enable `memlog-keep-small-allocations`
to record all the allocations, however this option has a significant
performance and memory overhead.
4. By default, stack traces use native stack traces, which does not contain any
thread information. To include the thread at time of allocation, set
`memlog-stack-mode` to `native with thread names`.
5. Restart Chrome.
6. Grab a [MemoryInfra][memory-infra] trace.
7. Save the trace.
8. To symbolize the trace:
1. Navigate to chrome://memory-internals.
* There will be an error message at the top if heap-profiling is not
supported on the current configuration
2. Enable heap profiling for the relevant processes. Future allocations will be
tracked. Refresh the page to view tracked processes.
* To enable tracking at process start, navigate to chrome://flags and search
for `memlog`.
3. To take a heap dump, click `save dump`. This is stored as a
[MemoryInfra][memory-infra] trace.
4. To symbolize the trace:
* Windows only: build `addr2line-pdb` from the chromium repository. For subsequent commands, add the flag `--addr2line-executable=<path_to_addr2lin-pdb>`
* If this is a local build, run the command `./third_party/catapult/tracing/bin/symbolize_trace --is-local-build <path_to_trace>`
* If this is an official Chrome build, run `./third_party/catapult/tracing/bin/symbolize_trace <path_to_trace>`. This will request authentication with google cloud storage to obtain symbol files [googlers only].
* If this is an official macOS or Linux Chrome build, add the flag `--use-breakpad-symbols`.
* If the trace is from a different device, add the flag `--only-symbolize-chrome-symbols`.
9. Turn off heap profiling in chrome://flags. Restart Chrome.
10. Load the (now symbolized) trace in chrome://tracing.
5. Load the (now symbolized) trace in chrome://tracing.
## How to obtain a heap dump (M66+, Android)