Out of memory crash

[zxcat]

Found in logs:

FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory

<--- Last few GCs --->

[1:0x2c82030]   701909 ms: Mark-sweep 1347.6 (1440.3) -> 1332.8 (1440.8) MB, 2512.3 / 0.0 ms  (average mu = 0.250, current mu = 0.162) allocation failure scavenge might not succeed
[1:0x2c82030]   704545 ms: Mark-sweep 1348.4 (1440.8) -> 1333.2 (1441.8) MB, 2031.1 / 0.0 ms  (average mu = 0.240, current mu = 0.229) allocation failure scavenge might not succeed


<--- JS stacktrace --->

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

    0: ExitFrame [pc: 0x287dc835be1d]
Security context: 0x11f39a29e6e9 <JSObject>
    1: add [0x11f39a291831](this=0x0b3fe94b9741 <Set map = 0x3f00aea041f9>,0x11f39a2c30f1 <String[10]: eventNames>)
    2: $set [0x18dedc299e01] [/usr/src/app/node_modules/mongoose/lib/document.js:829] [bytecode=0x18dcbb43ca21 offset=519](this=0x0b3fe94b9311 <model map = 0x2d590ee7fc99>,path=0x11f39a2c30f1 <String[10]: eventNames>,val=0x0b3fe94b92f1 <JSArray...

2:

    3: cleanModifiedSubpaths(aka cleanModifiedSubpaths) [0xa571d2ca6e1] [/usr/src/app/node_modules/mongoose/lib/helpers/document/cleanModifiedSubpaths.js:22] [bytecode=0x8ec7b28ea59 offset=182](this=0x16ffdbf026f1 <undefined>,doc=0x2a6a10254871 <model map = 0x2023dbe7e119>,path=0x124a7d310...

3:

    3: /* anonymous */ [0x2fe7a658e29] [/usr/src/app/node_modules/mongoose/lib/statemachine.js:133] [bytecode=0x296280e71451 offset=87](this=0x02fe7a657aa1 <ctor map = 0x38ccfc586249>)
    4: arguments adaptor frame: 1->0
    5: forEach [0x243670a13131] [/usr/src/app/node_modules/mon...

4:

    3: from [0x22e31019f849] [buffer.js:~199] [pc=0x27d855897a0a](this=0x1c1f8f6531f1 <JSFunction Buffer (sfi = 0x22e310195f79)>,value=0x1393e883ce11 <Uint8Array map = 0x123a60184cf9>,encodingOrOffset=0x1389d9a826f1 <undefined>,length=0x1389d9a826f1 <undefined>)
    4: arguments adap...

5:

    1: /* anonymous */ [0x2d0f495f0e11] [/usr/src/app/node_modules/mongoose/lib/schema.js:~539] [pc=0xee240c57aea](this=0x20371cea45d9 <Schema map = 0xd9817105119>,path=0x238f1d0590e9 <String[7]: account>,obj=0x2c5215d826f1 <undefined>)
    2: arguments adaptor frame: 1->2
    3: applyTimestampsToChildren(aka applyTimestampsToChildren) [0x2f7389c59031] [/usr/...

6:

    2: /* anonymous */ [0x352330d7c249] [/usr/src/app/node_modules/mongoose/lib/model.js:217] [bytecode=0x1c5429305c51 offset=17](this=0x0cb3adacea39 <model map = 0x3534b2813921>,options=0x0cb3adad03a9 <SaveOptions map = 0x125b77312169>,callback=0x0cb3adad1e29 <JSFunction $__handleSave (sfi = 0x39cef79a63a1)>)
    3: /* ...

7 (several):

    0: builtin exit frame: parse(this=0x3baa9cc91a21 <Object map = 0x3d8ff70842a9>,0x2380bda93021 <Very long string[69098]>,0x3baa9cc91a21 <Object map = 0x3d8ff70842a9>)

    1: handlerWrapper [0xa9484d85ba9] [/usr/src/app/node_modules/cyberway-core-service/src/services/BlockSubscribe.js:~249] [pc=0x1b7049868be2](this=0x0a9484d85b19 <Subscription map = 0x17066d0836a1>,message=0x09284a149c31 <Mes...

Looks like something wrong with mongoose

[zxcat]

increasing nodejs memory to 4Gb didn't resolve the issue.
changing MAX_IN_FLIGHT didn't help too.

OOM only happens while resync events, service works fine after resync.
looks like there is some memory leak or queue "overflow".