sails: Memory leak when lifting and lowering Sails repeatedly in automated tests

Node version: v10.16.0 Sails version (sails): 1.2.3 ORM hook version (sails-hook-orm): Not using this. Sockets hook version (sails-hook-sockets): Not using this. Organics hook version (sails-hook-organics): Not using this. Grunt hook version (sails-hook-grunt): Not using this. Uploads hook version (sails-hook-uploads): Not using this. DB adapter & version (e.g. sails-mysql@5.55.5): Not using this. Skipper adapter & version (e.g. skipper-s3@5.55.5): Not using this.

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I’ve looked through all issued related to memory leaks, but none of them describes my case.

When testing a sails application, we ‘lift’ and ‘lower’ for each test. We have an extensive test suite, and we now experience OOM errors when running tests. We use the supported constructor as mentioned here: https://sailsjs.com/documentation/concepts/programmatic-usage

I managed to make a tiny script that clearly shows the increasing memory footprint.

const Sails = require("sails").Sails;

(async () => {
  for(let i = 0; i < 500000; i++){
    await startStop();
    if(i % 100 === 0) printUsage();
  }
})();

async function startStop() {
  const sails = new Sails();
  await sails.lift({ log: { noShip: true }, session: { secret: 'x' } });
  await sails.lower();
}

function printUsage() {
  const used = process.memoryUsage().heapUsed / 1024 / 1024;
  console.log(`Process uses ${Math.round(used * 100) / 100} MB`);
}

It takes awhile, but eventually it runs out of memory. Some memory is clearly being freed by the garbage collector, but some is never freed. Output from my console is:

ath88@lipton:~/test/sails-test$ node index.js 
Process uses 23.84 MB
Process uses 29.99 MB
Process uses 34.82 MB
...
Process uses 1271.33 MB
Process uses 1286.41 MB
Process uses 1287.27 MB

<--- Last few GCs --->

[11916:0x348d020]   500144 ms: Mark-sweep 1239.6 (1418.2) -> 1239.6 (1395.2) MB, 713.7 / 0.1 ms  (average mu = 0.830, current mu = 0.000) last resort GC in old space requested
[11916:0x348d020]   500840 ms: Mark-sweep 1239.6 (1395.2) -> 1239.6 (1395.2) MB, 695.9 / 0.1 ms  (average mu = 0.711, current mu = 0.000) last resort GC in old space requested

<--- JS stacktrace --->

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

    0: ExitFrame [pc: 0xf994af5be1d]
    1: StubFrame [pc: 0xf994af5a1bb]
Security context: 0x345970a9e6e9 <JSObject>
    2: set [0x345970a937b9](this=0x221dd5702859 <JSWeakMap>,0x300fe1705e19 <JSFunction wrapper (sfi = 0x16c7dcce5979)>,0x300fe1705da9 <JSArray[10]>)
    3: /* anonymous */ [0x221dd57069d1] [/home/ath88/test/sails-test/node_modules/@sailshq/lodash/lib/index.js:~7645] [pc=0xf994af707d4](this=0x1e819d409ad1 <JSFunction lodash...

FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - JavaScript heap out of memory
 1: 0x8f9d10 node::Abort() [node]
 2: 0x8f9d5c  [node]
 3: 0xaffd0e v8::Utils::ReportOOMFailure(v8::internal::Isolate*, char const*, bool) [node]
 4: 0xafff44 v8::internal::V8::FatalProcessOutOfMemory(v8::internal::Isolate*, char const*, bool) [node]
 5: 0xef4152  [node]
 6: 0xf0396f v8::internal::Heap::AllocateRawWithRetryOrFail(int, v8::internal::AllocationSpace, v8::internal::AllocationAlignment) [node]
 7: 0xecc9c6 v8::internal::Factory::AllocateRawArray(int, v8::internal::PretenureFlag) [node]
 8: 0xecd24a v8::internal::Factory::NewFixedArrayWithFiller(v8::internal::Heap::RootListIndex, int, v8::internal::Object*, v8::internal::PretenureFlag) [node]
 9: 0xecd2f0 v8::internal::Handle<v8::internal::FixedArray> v8::internal::Factory::NewFixedArrayWithMap<v8::internal::FixedArray>(v8::internal::Heap::RootListIndex, int, v8::internal::PretenureFlag) [node]
10: 0x10089b1 v8::internal::HashTable<v8::internal::ObjectHashTable, v8::internal::ObjectHashTableShape>::NewInternal(v8::internal::Isolate*, int, v8::internal::PretenureFlag) [node]
11: 0x1008a0e v8::internal::HashTable<v8::internal::ObjectHashTable, v8::internal::ObjectHashTableShape>::New(v8::internal::Isolate*, int, v8::internal::PretenureFlag, v8::internal::MinimumCapacity) [node]
12: 0x101926f v8::internal::HashTable<v8::internal::ObjectHashTable, v8::internal::ObjectHashTableShape>::EnsureCapacity(v8::internal::Handle<v8::internal::ObjectHashTable>, int, v8::internal::PretenureFlag) [node]
13: 0x102b618 v8::internal::ObjectHashTable::Put(v8::internal::Handle<v8::internal::ObjectHashTable>, v8::internal::Handle<v8::internal::Object>, v8::internal::Handle<v8::internal::Object>, int) [node]
14: 0x102b836 v8::internal::JSWeakCollection::Set(v8::internal::Handle<v8::internal::JSWeakCollection>, v8::internal::Handle<v8::internal::Object>, v8::internal::Handle<v8::internal::Object>, int) [node]
15: 0x1142060 v8::internal::Runtime_WeakCollectionSet(int, v8::internal::Object**, v8::internal::Isolate*) [node]
16: 0xf994af5be1d 
Aborted (core dumped)

As far as I can see from snapshots with Chrome DevTools, async is getting re-required and never removed from memory.

If would be awesome to eliminate this memory leak, so we can continue our testing practices, with the supported ‘programmatic usage’.