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Preventing MaxListenersExceededWarning #4421

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merged 6 commits into from
Sep 1, 2022
Merged

Preventing MaxListenersExceededWarning #4421

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ebdbb50
preventing MaxListenersExceededWarning
dadepo Aug 15, 2022
7802a2a
Merge branch 'unstable' into dadepo/fix-eventemitter-memory-log
dadepo Aug 23, 2022
d86bb68
set setMaxListeners to Infinity
dadepo Aug 23, 2022
72f211f
Removing setting max listeners to infinity in cases where it has not …
dadepo Aug 24, 2022
ccd11c1
set max listeners for ValidatorEventEmitter to infinity
dadepo Aug 24, 2022
ea7ef2f
revert ordering of promise race
dadepo Aug 30, 2022
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4 changes: 4 additions & 0 deletions packages/beacon-node/src/network/reqresp/reqResp.ts
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
import {setMaxListeners} from "node:events";
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Shame we have to introduce a nodejs specific api here.

Later we can pass down a signal from the top-level beacon node and avoid creating a new signal here.

import {Connection} from "libp2p";
import {HandlerProps} from "libp2p/src/registrar";
import LibP2p from "libp2p";
Expand Down Expand Up @@ -71,6 +72,9 @@ export class ReqResp implements IReqResp {

async start(): Promise<void> {
this.controller = new AbortController();
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// We set infinity to prevent MaxListenersExceededWarning which get logged when listeners > 10
// Since it is perfectly fine to have listeners > 10
setMaxListeners(Infinity, this.controller.signal);
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Responsible for the warning observed in the trace:

(node:56301) MaxListenersExceededWarning: Possible EventTarget memory leak detected. 11 abort listeners added to [AbortSignal]. Use events.setMaxListeners() to increase limit
    at AbortSignal.[kNewListener] (node:internal/event_target:426:17)
    at AbortSignal.[kNewListener] (node:internal/abort_controller:173:24)
    at AbortSignal.addEventListener (node:internal/event_target:535:23)
    at anySignal (/Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/node_modules/any-signal/index.js:27:12)
    at withTimeout (file:///Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/packages/utils/src/timeout.ts:11:34)
    at sendRequest (file:///Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/packages/beacon-node/src/network/reqresp/request/index.ts:87:50)
    at ReqResp.sendRequest (file:///Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/packages/beacon-node/src/network/reqresp/reqResp.ts:154:28)
    at ReqResp.status (file:///Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/packages/beacon-node/src/network/reqresp/reqResp.ts:92:23)
    at PeerManager.requestStatus (file:///Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/packages/beacon-node/src/network/peers/peerManager.ts:359:46)
    at file:///Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/packages/beacon-node/src/network/peers/peerManager.ts:368:56

for (const [method, version, encoding] of protocolsSupported) {
await this.libp2p.handle(
formatProtocolId(method, version, encoding),
Expand Down
4 changes: 4 additions & 0 deletions packages/beacon-node/src/node/nodejs.ts
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
import {setMaxListeners} from "node:events";
import LibP2p from "libp2p";
import {Registry} from "prom-client";

Expand Down Expand Up @@ -118,6 +119,9 @@ export class BeaconNode {
metricsRegistries = [],
}: IBeaconNodeInitModules): Promise<T> {
const controller = new AbortController();
// We set infinity to prevent MaxListenersExceededWarning which get logged when listeners > 10
// Since it is perfectly fine to have listeners > 10
setMaxListeners(Infinity, controller.signal);
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Can you commit as comment the stack trace proving that this very specific event emitter gets more that 10 listeners?

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The signal here was what was passed down and triggered this:

(node:56301) MaxListenersExceededWarning: Possible EventTarget memory leak detected. 11 abort listeners added to [AbortSignal]. Use events.setMaxListeners() to increase limit
    at AbortSignal.[kNewListener] (node:internal/event_target:426:17)
    at AbortSignal.[kNewListener] (node:internal/abort_controller:173:24)
    at AbortSignal.addEventListener (node:internal/event_target:535:23)
    at JsonRpcHttpClient.fetchJsonOneUrl (file:///Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/packages/beacon-node/src/eth1/provider/jsonRpcHttpClient.ts:194:24)
    at JsonRpcHttpClient.fetchJson (file:///Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/packages/beacon-node/src/eth1/provider/jsonRpcHttpClient.ts:160:27)
    at retry.retries._b (file:///Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/packages/beacon-node/src/eth1/provider/jsonRpcHttpClient.ts:125:27)
    at retry (file:///Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/packages/utils/src/retry.ts:33:20)
    at JsonRpcHttpClient.fetchWithRetries (file:///Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/packages/beacon-node/src/eth1/provider/jsonRpcHttpClient.ts:119:23)
    at ExecutionEngineHttp.exchangeTransitionConfigurationV1 (file:///Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/packages/beacon-node/src/execution/engine/http.ts:298:27)
    at BeaconChain.exchangeTransitionConfiguration (file:///Users/dadepoaderemi/Documents/work/chainsafe/official/lodestar/packages/beacon-node/src/chain/chain.ts:573:62)
Aug-17 21:32:00.064[CHAI

const signal = controller.signal;

// start db if not already started
Expand Down
2 changes: 1 addition & 1 deletion packages/validator/src/services/attestation.ts
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Expand Up @@ -52,7 +52,7 @@ export class AttestationService {
// A validator should create and broadcast the attestation to the associated attestation subnet when either
// (a) the validator has received a valid block from the expected block proposer for the assigned slot or
// (b) one-third of the slot has transpired (SECONDS_PER_SLOT / 3 seconds after the start of slot) -- whichever comes first.
await Promise.race([sleep(this.clock.msToSlot(slot + 1 / 3), signal), this.waitForBlockSlot(slot)]);
await Promise.race([this.waitForBlockSlot(slot), sleep(this.clock.msToSlot(slot + 1 / 3), signal)]);
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Why is it necessary to change the order here?

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It was not a necessity. It was changed to align with the text of the spec, which was placed as a comment

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What do you mean the spec? Where does the spec specify the order of promises in javascript?

this.metrics?.attesterStepCallProduceAttestation.observe(this.clock.secFromSlot(slot + 1 / 3));

// Beacon node's endpoint produceAttestationData return data is not dependant on committeeIndex.
Expand Down