Possible memory leak in `parse`

[alanshaw]

Parsing a stream of ndjson entries causes OOM in Node.js 20:

<--- Last few GCs --->

[92603:0x158008000]   106289 ms: Mark-Compact 4050.2 (4134.2) -> 4035.5 (4135.5) MB, 924.04 / 0.00 ms  (average mu = 0.116, current mu = 0.034) allocation failure; scavenge might not succeed
[92603:0x158008000]   107247 ms: Mark-Compact 4051.7 (4135.7) -> 4036.7 (4136.7) MB, 927.25 / 0.00 ms  (average mu = 0.076, current mu = 0.033) allocation failure; scavenge might not succeed


<--- JS stacktrace --->

FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory
 1: 0x1002d0588 node::Abort() [/usr/local/bin/node]
 2: 0x1002d0770 node::ModifyCodeGenerationFromStrings(v8::Local<v8::Context>, v8::Local<v8::Value>, bool) [/usr/local/bin/node]
 3: 0x10045233c v8::internal::V8::FatalProcessOutOfMemory(v8::internal::Isolate*, char const*, v8::OOMDetails const&) [/usr/local/bin/node]
 4: 0x1006269f4 v8::internal::Heap::GarbageCollectionReasonToString(v8::internal::GarbageCollectionReason) [/usr/local/bin/node]
 5: 0x10062a8a8 v8::internal::Heap::CollectGarbageShared(v8::internal::LocalHeap*, v8::internal::GarbageCollectionReason) [/usr/local/bin/node]
 6: 0x10062730c v8::internal::Heap::PerformGarbageCollection(v8::internal::GarbageCollector, v8::internal::GarbageCollectionReason, char const*) [/usr/local/bin/node]
 7: 0x100625094 v8::internal::Heap::CollectGarbage(v8::internal::AllocationSpace, v8::internal::GarbageCollectionReason, v8::GCCallbackFlags) [/usr/local/bin/node]
 8: 0x10061bce8 v8::internal::HeapAllocator::AllocateRawWithLightRetrySlowPath(int, v8::internal::AllocationType, v8::internal::AllocationOrigin, v8::internal::AllocationAlignment) [/usr/local/bin/node]
 9: 0x10061c548 v8::internal::HeapAllocator::AllocateRawWithRetryOrFailSlowPath(int, v8::internal::AllocationType, v8::internal::AllocationOrigin, v8::internal::AllocationAlignment) [/usr/local/bin/node]
10: 0x10060154c v8::internal::Factory::NewFillerObject(int, v8::internal::AllocationAlignment, v8::internal::AllocationType, v8::internal::AllocationOrigin) [/usr/local/bin/node]
11: 0x1009e8f5c v8::internal::Runtime_AllocateInYoungGeneration(int, unsigned long*, v8::internal::Isolate*) [/usr/local/bin/node]
12: 0x100d48c44 Builtins_CEntry_Return1_ArgvOnStack_NoBuiltinExit [/usr/local/bin/node]
13: 0x100cf7038 Builtins_AsyncFunctionAwaitUncaught [/usr/local/bin/node]
14: 0x10606df24 
15: 0x100cf7210 Builtins_AsyncFunctionAwaitResolveClosure [/usr/local/bin/node]
16: 0x100da4fb8 Builtins_PromiseFulfillReactionJob [/usr/local/bin/node]
17: 0x100ce6b94 Builtins_RunMicrotasks [/usr/local/bin/node]
18: 0x100cbe3f4 Builtins_JSRunMicrotasksEntry [/usr/local/bin/node]
19: 0x100593f7c v8::internal::(anonymous namespace)::Invoke(v8::internal::Isolate*, v8::internal::(anonymous namespace)::InvokeParams const&) [/usr/local/bin/node]
20: 0x100594468 v8::internal::(anonymous namespace)::InvokeWithTryCatch(v8::internal::Isolate*, v8::internal::(anonymous namespace)::InvokeParams const&) [/usr/local/bin/node]
21: 0x100594644 v8::internal::Execution::TryRunMicrotasks(v8::internal::Isolate*, v8::internal::MicrotaskQueue*) [/usr/local/bin/node]
22: 0x1005bb700 v8::internal::MicrotaskQueue::RunMicrotasks(v8::internal::Isolate*) [/usr/local/bin/node]
23: 0x1005bbe9c v8::internal::MicrotaskQueue::PerformCheckpoint(v8::Isolate*) [/usr/local/bin/node]
24: 0x1004bff34 v8::internal::MaybeHandle<v8::internal::Object> v8::internal::(anonymous namespace)::HandleApiCallHelper<false>(v8::internal::Isolate*, v8::internal::Handle<v8::internal::HeapObject>, v8::internal::Handle<v8::internal::FunctionTemplateInfo>, v8::internal::Handle<v8::internal::Object>, unsigned long*, int) [/usr/local/bin/node]
25: 0x1004bf62c v8::internal::Builtin_HandleApiCall(int, unsigned long*, v8::internal::Isolate*) [/usr/local/bin/node]
26: 0x100d48b24 Builtins_CEntry_Return1_ArgvOnStack_BuiltinExit [/usr/local/bin/node]
27: 0x1061b1548 
28: 0x100cbe50c Builtins_JSEntryTrampoline [/usr/local/bin/node]
29: 0x100cbe1f4 Builtins_JSEntry [/usr/local/bin/node]
30: 0x100593fa4 v8::internal::(anonymous namespace)::Invoke(v8::internal::Isolate*, v8::internal::(anonymous namespace)::InvokeParams const&) [/usr/local/bin/node]
31: 0x1005933f0 v8::internal::Execution::Call(v8::internal::Isolate*, v8::internal::Handle<v8::internal::Object>, v8::internal::Handle<v8::internal::Object>, int, v8::internal::Handle<v8::internal::Object>*) [/usr/local/bin/node]
32: 0x10046dcc8 v8::Function::Call(v8::Local<v8::Context>, v8::Local<v8::Value>, int, v8::Local<v8::Value>*) [/usr/local/bin/node]
33: 0x100204d3c node::InternalCallbackScope::Close() [/usr/local/bin/node]
34: 0x10020501c node::InternalMakeCallback(node::Environment*, v8::Local<v8::Object>, v8::Local<v8::Object>, v8::Local<v8::Function>, int, v8::Local<v8::Value>*, node::async_context) [/usr/local/bin/node]
35: 0x10021b46c node::AsyncWrap::MakeCallback(v8::Local<v8::Function>, int, v8::Local<v8::Value>*) [/usr/local/bin/node]
36: 0x100399254 node::StreamBase::CallJSOnreadMethod(long, v8::Local<v8::ArrayBuffer>, unsigned long, node::StreamBase::StreamBaseJSChecks) [/usr/local/bin/node]
37: 0x10039a8c0 node::EmitToJSStreamListener::OnStreamRead(long, uv_buf_t const&) [/usr/local/bin/node]
38: 0x10039eba0 node::LibuvStreamWrap::OnUvRead(long, uv_buf_t const*) [/usr/local/bin/node]
39: 0x10039f324 node::LibuvStreamWrap::ReadStart()::$_1::__invoke(uv_stream_s*, long, uv_buf_t const*) [/usr/local/bin/node]
40: 0x100ca7f48 uv__stream_io [/usr/local/bin/node]
41: 0x100caf84c uv__io_poll [/usr/local/bin/node]
42: 0x100c9dd38 uv_run [/usr/local/bin/node]
43: 0x100205754 node::SpinEventLoopInternal(node::Environment*) [/usr/local/bin/node]
44: 0x100310984 node::NodeMainInstance::Run(node::ExitCode*, node::Environment*) [/usr/local/bin/node]
45: 0x10031072c node::NodeMainInstance::Run() [/usr/local/bin/node]
46: 0x10029c4b0 node::LoadSnapshotDataAndRun(node::SnapshotData const**, node::InitializationResultImpl const*) [/usr/local/bin/node]
47: 0x10029c7d0 node::Start(int, char**) [/usr/local/bin/node]
48: 0x105e250f4 

[rvagg]

interesting! do you happen to have a good source of data I could reproduce this with?

[rvagg]

Here's my attempt at reproducing something approximating what you describe:

import { garbage } from '@ipld/garbage'
import * as json from '@ipld/dag-json'

const objTargetSize = 1024 * 100 // 100k

const utf8Dec = new TextDecoder()
const utf8Enc = new TextEncoder()

function nfmt (n) {
  return Intl.NumberFormat().format(n)
}

let lastGbg
const src = {
  async * [Symbol.asyncIterator] () {
    while (true) {
      await new Promise((resolve) => setImmediate(resolve))
      lastGbg = garbage(objTargetSize)
      yield utf8Dec.decode(json.encode(lastGbg))
    }
  }
}

let c = 0
let byts = 0

for await (const line of src) {
  let obj
  try {
    obj = json.decode(utf8Enc.encode(line))
  } catch (err) {
    if (err.message === 'Invalid encoded CID form' ||
      err.message === 'To parse non base32 or base58btc encoded CID multibase decoder must be provided' ||
      err.message === 'Non-base58btc character') {
      // @ipld/garbage may throw up an object with `{'/':'whatever'}` that @ipld/dag-json won't bork at encoding (yet)
      continue
    }
    console.log('Got error:')
    console.log(err.message)
    console.log('On content:')
    console.log(line)
    console.log('Object:')
    console.log(lastGbg)
  }
  if (obj === undefined) {
    throw new Error('undefined')
  }
  byts += line.length
  if (++c % 1000 === 0) {
    console.log('%s lines / %s Mb processed', nfmt(c), nfmt(Math.floor(byts / 1024 / 1024)))
  }
}

But running it (Node.js v20.5.1) just seems to hover somewhere above 100k in memory. I'll leave it running a bit longer but as of writing I've got up to ~800k lines / 50 Gb worth of decoding. Can you help tweak this to replicate your environment a bit better @alanshaw?