Memory leak?

[waj]

Maybe I'm doing something wrong, but if I continuously create and destroy JavaScript VM instances the process memory increases all the time:

runjs() ->
  {ok, Js} = js_driver:new(),
  js_driver:destroy(Js),
  runjs().

Any thoughts? Should I do this in some other way?

[cmeiklejohn]

@waj can you provide the version of Erlang/OTP you are using?

[strange]

I'm experiencing the same behavior on my end (R16B01 and R15B03, OS X and Linux respectively).

run(0) -> ok;
run(N) ->
    {ok, Ctx} = js_driver:new(),
    true = js_driver:destroy(Ctx),
    run(N - 1).

Running run(10000) a few times will quickly eat up all of my memory. Closing the shell will free it up again.

[systra]

Any solution available?

[joedevivo]

I tried this in Erlang R16B02 on OS X and was not able to reproduce. So I just went all in with this function.

run(N) ->
    case N rem 10000 of
      0 -> io:format("~p vms~n", [N]);
      _ -> ok
    end,
    {ok, Ctx} = js_driver:new(),
    true = js_driver:destroy(Ctx),
    run(N + 1).

which I figured was sure to expose the issue; however, it was only able to use at most 1GB of memory, and it reclaimed memory, just not as quickly as I'd have expected it to.

Even still, this is a contrived example that really isn't a good use case. Is there some example of an application that this is causing a problem for? If there's no further activity on this issue, we'll consider a fix not necessary.

[systra]

I did some tests on various platforms (Centos, OSX) and Erlang releases - same effect = memory leaks.

Please try to make simple test on the OS X:

• Run VM with additional environment variable:

MallocStackLogging=1 erl -pa .....

• Make test call:

{ok, JS} = js_driver:new().
js_driver:destroy(JS).

• Run leaks command on the shell using beam.smp PID:

leaks <PID>

You should see memory leaks with call stack like this:

Process:         beam.smp [3627]
Path:            /opt/erlang/r16b03/erts-5.10.4/bin/beam.smp
Load Address:    0x10f848000
Identifier:      beam.smp
Version:         0
Code Type:       X86-64
Parent Process:  zsh [74734]

Date/Time:       2014-03-19 08:51:27.414 +0100
OS Version:      Mac OS X 10.9.2 (13C64)
Report Version:  7

leaks Report Version:  2.0
Process 3627: 1386 nodes malloced for 7737 KB
Process 3627: 121 leaks for 16096 total leaked bytes.
Leak: 0x7f8e5be03780  size=96  zone: DefaultMallocZone_0x10fd83000
    0x00000001 0x00000000 0x13b43ee0 0x00000001     .........>......
    0x0000004e 0x00000000 0x5be02b40 0x00007f8e     N.......@+.[....
    0x00000000 0x00000000 0x00000000 0x00000000     ................
    0x00000000 0x00000000 0x0fdee000 0x00000001     ................
    0x000001f0 0x00001a00 0x0000002a 0x00000000     ........*.......
    0x5be066c0 0x00007f8e 0x5d02c3c8 0x00007f8e     .f.[.......]....
    Call stack: [thread 0x111603000]: | erts_port_output | process spidermonkey_drv.c:230 | sm_initialize spidermonkey.c:158 | js_NewObjectWithGivenProto | js_NewScope | JS_malloc | malloc | malloc_zone_malloc 
Leak: 0x7f8e5be037e0  size=32  zone: DefaultMallocZone_0x10fd83000
    0x00000009 0x00000000 0x0fded000 0x00000001     ................
    0x80000001 0xffffffff 0x80000001 0xffffffff     ................
    Call stack: [thread 0x111603000]: | erts_port_output | process spidermonkey_drv.c:230 | sm_initialize spidermonkey.c:159 | JS_InitStandardClasses | js_InitFunctionAndObjectClasses | js_InitFunctionClass | JS_InitClass | js_SetClassPrototype | js_DefineProperty | js_DefineNativeProperty | js_AddScopeProperty | js_AllocSlot | js_ReallocSlots | JS_realloc | realloc | malloc_zone_malloc 
Leak: 0x7f8e5be03800  size=32  zone: DefaultMallocZone_0x10fd83000
    0x00000009 0x00000000 0x0fdee040 0x00000001     ........@.......
    0x80000001 0xffffffff 0x80000001 0xffffffff     ................
    Call stack: [thread 0x111603000]: | erts_port_output | process spidermonkey_drv.c:230 | sm_initialize spidermonkey.c:159 | JS_InitStandardClasses | js_InitFunctionAndObjectClasses | js_InitObjectClass | JS_InitClass | js_SetClassPrototype | js_DefineProperty | js_DefineNativeProperty | js_AddScopeProperty | js_AllocSlot | js_ReallocSlots | JS_realloc | realloc | malloc_zone_malloc 
Leak: 0x7f8e5be03830  size=64  zone: DefaultMallocZone_0x10fd83000
...
...

I have a suspicion that the JS_DestroyContext function doesn't perform properly garbage collection of the memory being used by cx's global object.

I have upgraded the spidermonkey to 1.8.5 and it seems to work properly now.

[eraserewind]

I'm having the same issue:

• Linux shive.r #1 SMP Tue Nov 4 15:43:28 CET 2014 armv7l GNU/Linux
• Erlang/OTP 17 [erts-6.1] [source] [smp:4:4] [async-threads:10] [kernel-poll:false]
• I'm using the latest erlang_js from git (bc8db2a), looks like it is using js-1.8.0-rc1.tar.gz.

I've attached the memory graph seen by Munin.