Memory leak in v8 CpuProfiler

[Hollerberg]

• Version: v8.4.0
• Platform: Windows 10 / Linux x86 32/64bit
• Subsystem: v8

Dear Node community, I am filing this ticket to make you aware of a memory leak in v8::CpuProfiler introduced in v8 versions used by Node 7.x / 8.x. My company uses v8::CpuProfiler APIs to render periodic samples of the running application and I noticed a continuous RSS size increase with Node.js version 7.x and 8.x. Earlier versions are not affected. I reported the issue a few weeks back in v8 monorail (https://bugs.chromium.org/p/v8/issues/detail?id=6623) but it did not receive too much attention so far.

[mscdex]

/cc @nodejs/v8

[danielkhan]

/cc @nodejs/diagnostics

[bnoordhuis]

I can confirm the issue and came to the same conclusion, that it's the ProfilerListener that is leaking the memory. A straightforward patch (see below) breaks a number of V8 tests however so this needs some more digging.

diff --git a/deps/v8/src/log.cc b/deps/v8/src/log.cc
index 7f029d8..57cd522 100644
--- a/deps/v8/src/log.cc
+++ b/deps/v8/src/log.cc
@@ -1854,6 +1854,7 @@ void Logger::SetUpProfilerListener() {
 void Logger::TearDownProfilerListener() {
   if (profiler_listener_->HasObservers()) return;
   removeCodeEventListener(profiler_listener_.get());
+  profiler_listener_.reset();
 }

 sampler::Sampler* Logger::sampler() {

[bnoordhuis]

Turns out the ProfilerListener is still used after TearDownProfilerListener()...

I have a new patch that passes V8's and node's test suites but it's a little gross. I'll see if I can spruce it up before I send it upstream.

diff --git a/deps/v8/src/profiler/cpu-profiler.cc b/deps/v8/src/profiler/cpu-profiler.cc
index 85f9d5e..3e7c474 100644
--- a/deps/v8/src/profiler/cpu-profiler.cc
+++ b/deps/v8/src/profiler/cpu-profiler.cc
@@ -275,6 +275,8 @@ void CpuProfiler::set_sampling_interval(base::TimeDelta value) {
 void CpuProfiler::ResetProfiles() {
   profiles_.reset(new CpuProfilesCollection(isolate_));
   profiles_->set_cpu_profiler(this);
+  Logger* logger = isolate_->logger();
+  logger->profiler_listener_.reset();
 }

 void CpuProfiler::CreateEntriesForRuntimeCallStats() {

[Hollerberg]

@bnoordhuis thanks a lot for your effort! is there a chance that this patch will be included into one of the next Node.js releases?

[interviewQ]

I am seeing this issue too with node 7 and 8. I see that the bug is closed. Which node release is the fix present in ?

[TimothyGu]

@interviewQ It was just fixed in Node.js yesterday (https://github.com/nodejs/node/pull/17512) so it will come with the next Node.js v8.x and v9.x. We no longer maintain v7.x.

Closing, since https://github.com/nodejs/node/pull/17512 fixes this.

[ofrobots]

Actually Node 9.3.0 released earlier this week should already contain the fix (please give it a shot and report back). For Node 8 the fix will be in the next release.

[interviewQ]

Thanks for the response. Would this get fixed in node 7 ?

Amaranth

On Thu, Dec 14, 2017 at 3:58 PM, Ali Ijaz Sheikh notifications@github.com wrote:

Actually Node 9.3.0 released earlier this week should already contain the fix (please give it a shot and report back). For Node 8 the fix will be in the next release.

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub https://github.com/nodejs/node/issues/14894#issuecomment-351872616, or mute the thread https://github.com/notifications/unsubscribe-auth/ASSkiQg8Ok5-eaj6NZ3aUuHlrmDMaYgvks5tAbZAgaJpZM4O6Wql .

[interviewQ]

Sorry, I missed your earlier message that this will not be fixed in node 7.

On Thu, Dec 14, 2017 at 4:10 PM, Amarnath Shanbhag < amarnathshanbhag@gmail.com> wrote:

Thanks for the response. Would this get fixed in node 7 ?

Amaranth

On Thu, Dec 14, 2017 at 3:58 PM, Ali Ijaz Sheikh <notifications@github.com

wrote:

Actually Node 9.3.0 released earlier this week should already contain the fix (please give it a shot and report back). For Node 8 the fix will be in the next release.

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub https://github.com/nodejs/node/issues/14894#issuecomment-351872616, or mute the thread https://github.com/notifications/unsubscribe-auth/ASSkiQg8Ok5-eaj6NZ3aUuHlrmDMaYgvks5tAbZAgaJpZM4O6Wql .