async version of fs utils causes OOM (but not sync) (faulty Promises?)

[yurydelendik]

Moved from nodejs/node#13337

• Version: v6.9.4
• Platform: Darwin Kernel Version 16.5.0
• Subsystem:

Based on mozilla/pdf.js#8419

STR:

1. clone https://github.com/yurydelendik/nodesegfault && npm install
   2.node pdf2svg.js

Expected result:
No node fatal error

Actual result:

...
<--- Last few GCs --->

   34764 ms: Mark-sweep 1149.4 (1215.2) -> 1148.8 (1190.2) MB, 14.0 / 0.0 ms [allocation failure] [GC in old space requested].
   34775 ms: Mark-sweep 1148.8 (1190.2) -> 1148.4 (1190.2) MB, 11.1 / 0.0 ms [allocation failure] [GC in old space requested].
   34794 ms: Mark-sweep 1148.4 (1190.2) -> 1148.4 (1156.2) MB, 18.9 / 0.0 ms [last resort gc].
   34802 ms: Mark-sweep 1148.4 (1156.2) -> 1148.4 (1156.2) MB, 7.7 / 0.0 ms [last resort gc].


<--- JS stacktrace --->

==== JS stack trace =========================================

Security context: 0x2684b5fcfb51 <JS Object>
    1: DoJoin(aka DoJoin) [native array.js:~129] [pc=0x45ab5998cec] (this=0x2684b5f04381 <undefined>,w=0x181e368c7f29 <JS Array[36]>,x=36,N=0x2684b5f043c1 <true>,J=0x2684b5f04411 <String[0]: >,I=0x2684b5fb46e1 <JS Function ConvertToString (SharedFunctionInfo 0x2684b5f52dc9)>)
    2: Join(aka Join) [native array.js:180] [pc=0x45ab590e3b2] (this=0x2684b5f04381 <undefined>,w=0x181e368c7f29 <JS Arr...

FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - JavaScript heap out of memory
 1: node::Abort() [/opt/local/bin/node]
 2: node::FatalException(v8::Isolate*, v8::Local<v8::Value>, v8::Local<v8::Message>) [/opt/local/bin/node]
 3: v8::Utils::ReportApiFailure(char const*, char const*) [/opt/local/bin/node]
 4: v8::Utils::ApiCheck(bool, char const*, char const*) [/opt/local/bin/node]
 5: v8::internal::V8::FatalProcessOutOfMemory(char const*, bool) [/opt/local/bin/node]
 6: v8::internal::Factory::NewRawTwoByteString(int, v8::internal::PretenureFlag) [/opt/local/bin/node]
 7: v8::internal::Runtime_StringBuilderConcat(int, v8::internal::Object**, v8::internal::Isolate*) [/opt/local/bin/node]
 8: 0x45ab54092a7
Abort trap: 6

Works fine when sync versions of writeFile or mkdir used (see mozilla/pdf.js#8461)

New finding: using non-native Node.js promises fixes the issue as well, e.g. global.Promise = undefined; forces to use PDF.js polyfill. This means there is no critical OOM leak on PDF.js side.

[Rob--W]

This can be closed. The explanation for the OOM is at mozilla/pdf.js#8540 and mozilla/pdf.js#8461 (comment).