Fix Travis OSX tests

[pichouk]

Summary
Travis tests on OSX seems to failed A LOT
because of this :

<--- Last few GCs --->

 1207511 ms: Mark-sweep 1362.1 (1435.5) -> 1362.1 (1435.5) MB, 2697.2 / 0.0 ms [allocation failure] [GC in old space requested].
 1210266 ms: Mark-sweep 1362.1 (1435.5) -> 1362.1 (1435.5) MB, 2754.3 / 0.1 ms [allocation failure] [GC in old space requested].
 1213441 ms: Mark-sweep 1362.1 (1435.5) -> 1385.1 (1411.5) MB, 3175.0 / 0.1 ms [last resort gc].
 1217347 ms: Mark-sweep 1385.1 (1411.5) -> 1408.1 (1411.5) MB, 3905.5 / 0.1 ms [last resort gc].

<--- JS stacktrace --->
==== JS stack trace =========================================
Security context: 0x5f7e3bcfb39 <JS Object>
    2: _tickCallback [internal/process/next_tick.js:~93] [pc=0x109f829ab8e3] (this=0x1c51837a7319 <a process with map 0x2c6ee9c11a91>)

==== Details ================================================
[2]: _tickCallback [internal/process/next_tick.js:~93] [pc=0x109f829ab8e3] (this=0x1c51837a7319 <a process with map 0x2c6ee9c11a91>) {

// optimized frame
--------- s o u r c e   c o d e ---------
fun...
FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - JavaScript heap out of memory
 1: node::Abort() [/Users/travis/.nvm/versions/node/v6.10.3/bin/node]
 2: node::FatalException(v8::Isolate*, v8::Local<v8::Value>, v8::Local<v8::Message>) [/Users/travis/.nvm/versions/node/v6.10.3/bin/node]
 3: v8::internal::V8::FatalProcessOutOfMemory(char const*, bool) [/Users/travis/.nvm/versions/node/v6.10.3/bin/node]
 4: v8::internal::Factory::NewStruct(v8::internal::InstanceType) [/Users/travis/.nvm/versions/node/v6.10.3/bin/node]
 5: v8::internal::Factory::NewTypeFeedbackInfo() [/Users/travis/.nvm/versions/node/v6.10.3/bin/node]
 6: v8::internal::FullCodeGenerator::MakeCode(v8::internal::CompilationInfo*) [/Users/travis/.nvm/versions/node/v6.10.3/bin/node]
 7: v8::internal::(anonymous namespace)::GenerateBaselineCode(v8::internal::CompilationInfo*) [/Users/travis/.nvm/versions/node/v6.10.3/bin/node]
 8: v8::internal::(anonymous namespace)::GetUnoptimizedCodeCommon(v8::internal::CompilationInfo*) [/Users/travis/.nvm/versions/node/v6.10.3/bin/node]
 9: v8::internal::Compiler::Compile(v8::internal::Handle<v8::internal::JSFunction>, v8::internal::Compiler::ClearExceptionFlag) [/Users/travis/.nvm/versions/node/v6.10.3/bin/node]
10: v8::internal::Runtime_CompileLazy(int, v8::internal::Object**, v8::internal::Isolate*) [/Users/travis/.nvm/versions/node/v6.10.3/bin/node]
11: 0x109f7ce092a7
12: 0x109f7ce34338
13: 0x109f829ab8e3
sh: line 1:  6601 Abort trap: 6           npm run test-only -- --maxWorkers 1
error Command failed with exit code 134.

I'm not sure of this, but it seems that the test runs out of memory. It seems to work if we use 3 workers.

[pichouk]

Ok, I know what you're thinking : "This is useless because it still failed" 😄
But know it failed for another reason ^^

Summary of all failing tests
 FAIL  __tests__/commands/add.js (415.695s)
  ● add with new dependency should be deterministic 3

    Timeout - Async callback was not invoked within timeout specified by jasmine.DEFAULT_TIMEOUT_INTERVAL.   
      at ontimeout (timers.js:386:14)
      at tryOnTimeout (timers.js:250:5)
      at Timer.listOnTimeout (timers.js:214:5)

Test Suites: 1 failed, 57 passed, 58 total
Tests:       1 failed, 6 skipped, 505 passed, 512 total
Snapshots:   53 passed, 53 total
Time:        476.803s
Ran all test suites.
error Command failed with exit code 1.
error Command failed with exit code 1.

It seems that there is some timeout errors, but I really don't know why this is happening...

[bestander]

Lol, thanks for looking at this, @pichouk.
I feel that the latest version of Node on Mac causes this memory leak.
It is weird that this gets fixed by increasing concurrency, maybe workers leak just a little bit.

Could you try specifying Node 6.9 for Travis OSX and see if it stops crashing with concurrency 1?
I decreased concurrency to 1 some time ago because I think it was failing because of timeouts a bit less often

[pichouk]

Doesn't seems to fix it. I tried locally (see https://github.com/pichouk/yarn/pull/6 ) and I still have memory issues if concurrency set to 1 with 6.9

[bestander]

Ok, let's merge this fix, still better than crash