(kad-dht) What is the cause of: CodeError: Query aborted

saul · November 2, 2023, 1:27am

I’m getting this error thrown occasionally (I can’t seem to get it to reproduce all that often), it crashes my entire program when it occurs.

file://node_modules/@libp2p/kad-dht/src/query/query-path.ts:227
      deferred.reject(new CodeError('Query aborted', 'ERR_QUERY_ABORTED'))
                      ^
CodeError: Query aborted
    at EventTarget.<anonymous> (file://node_modules/@libp2p/kad-dht/src/query/query-path.ts:227:23)
    at EventTarget.[nodejs.internal.kHybridDispatch] (node:internal/event_target:757:20)
    at EventTarget.dispatchEvent (node:internal/event_target:692:26)
    at abortSignal (node:internal/abort_controller:369:10)
    at AbortController.abort (node:internal/abort_controller:403:5)
    at EventTarget.onAbort (file://node_modules/any-signal/src/index.ts:14:16)
    at EventTarget.[nodejs.internal.kHybridDispatch] (node:internal/event_target:757:20)
    at EventTarget.dispatchEvent (node:internal/event_target:692:26)
    at abortSignal (node:internal/abort_controller:369:10)
    at AbortController.abort (node:internal/abort_controller:403:5) {
  code: 'ERR_QUERY_ABORTED',
  props: {}
}

My program has gotten quite large and is doing a lot of things simultaneously using Libp2p and Helia. and I am having a lot of trouble figuring out what precisely is causing this error or why it only occurs sometimes.

Shortly before this the logger produces a couple of errors:

libp2p:yamux frame for missing stream id=21
libp2p:connection-manager:dial-queue:error error during dial ... ECONNRESET ENETUNREACH
libp2p:kad-dht:wan:query ... ECONNRESET ENETUNREACH

But I don’t think these are the cause since it is throwing the entire program (uncaught) and it is only failing to dial a peer.

I know this doesn’t provide all the details necessary to debug this issue but if someone could point me in the right direction of things to more closely look at or test, it would be much appreciated.

saul · November 12, 2023, 7:47pm

Looks like it was due to a deferred promise not being handled right:

github.com/libp2p/js-libp2p

Possible unhandleable crash in kad-dht

opened 07:39PM - 07 Nov 23 UTC

closed 06:15AM - 10 Nov 23 UTC

saul-jb

need/triage

- **Version**: - libp2p: 0.46.16 - @libp2p/kad-dht: 10.0.11  - **Platform**: Linux 5.15.0-88-generic Ubuntu x86_64 GNU/Linux  - **Subsystem**: kad-dht  #### Severity: ?  #### Description:  I have been downloading many blocks in parallel via Helia and on (rare) occasions it would crash without much of a trace: ``` file://node_modules/@libp2p/kad-dht/src/query/query-path.ts:227 deferred.reject(new CodeError('Query aborted', 'ERR_QUERY_ABORTED')) ^ CodeError: Query aborted at EventTarget.<anonymous> (file://node_modules/@libp2p/kad-dht/src/query/query-path.ts:227:23) at EventTarget.[nodejs.internal.kHybridDispatch] (node:internal/event_target:757:20) at EventTarget.dispatchEvent (node:internal/event_target:692:26) at abortSignal (node:internal/abort_controller:369:10) at AbortController.abort (node:internal/abort_controller:403:5) at EventTarget.onAbort (file://node_modules/any-signal/src/index.ts:14:16) at EventTarget.[nodejs.internal.kHybridDispatch] (node:internal/event_target:757:20) at EventTarget.dispatchEvent (node:internal/event_target:692:26) at abortSignal (node:internal/abort_controller:369:10) at AbortController.abort (node:internal/abort_controller:403:5) { code: 'ERR_QUERY_ABORTED', props: {} } ``` Further debugging shows that the abort signal triggering this can be called from [bitswap](https://github.com/ipfs/js-ipfs-bitswap/blob/6c441b81cc49c07386e37ed06a1406e2136cb85a/src/bitswap.ts#L279) #### Steps to reproduce the error:  Unfortunately I can't seem to trigger this reliably. The error is thrown in [query-path.ts#L227](https://github.com/libp2p/js-libp2p/blob/master/packages/kad-dht/src/query/query-path.ts#L227). I believe this error is thrown and is uncatchable if the following steps happen: - The deferred promise is created. [query-path.ts#L240](https://github.com/libp2p/js-libp2p/blob/master/packages/kad-dht/src/query/query-path.ts#L240) - The iterable yields. [query-path.ts#L247](https://github.com/libp2p/js-libp2p/blob/master/packages/kad-dht/src/query/query-path.ts#L247) - The deferred promise is rejected before the `.next` is called on the iterator AND before it is resolved. [query-path.ts#L227](https://github.com/libp2p/js-libp2p/blob/master/packages/kad-dht/src/query/query-path.ts#L227) - Since the promise is rejected before it is awaited, it is thrown outside of the iterable context and cannot be caught. [query-path.ts#L239](https://github.com/libp2p/js-libp2p/blob/master/packages/kad-dht/src/query/query-path.ts#L239) In case that is not clear enough here is some code illustrating the error when everything aligns: ```javascript import defer from 'p-defer'; async function * toGenerator () { let defered = defer(); // Resolve soon. setTimeout(() => defered.resolve(), 10); for (;;) { // Wait for the deferred to be resolved await defered.promise; defered = defer(); // Reject later. setTimeout(() => defered.reject("Query aborted"), 10); yield; } } const itr = toGenerator(); try { // First iteration should resolve. await itr.next(); // A timer allows the promise to reject before the .next() call. await new Promise(r => setTimeout(r, 30)); // The toGenerator iterator will throw an uncatchable error before it gets here. await itr.next(); } catch (error) { // Error will not be catchable. } ``` It's possible that I am barking up the wrong tree here and my crash is caused by something else but after many hours of debugging it is the only possibility that I can think of that causes this issue.

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(kad-dht) What is the cause of: CodeError: Query aborted

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