AndreMaz
commented
5 years ago Could you create a repro repo?
Closed nmarus closed 1 year ago
AndreMaz
commented
5 years ago Could you create a repro repo?
nmarus
commented
5 years ago I can, but this single file example will generate the error on single instance for me. After some testing with this, it seems related to number of services. 3 service with 3 actions each does not generate the error, 10 with 10 each does.
const { ServiceBroker } = require('moleculer');
const brokerConfig = {
metrics: false,
cacher: {
type: 'Memory',
},
registry: {
strategy: 'Latency',
strategyOptions: {
sampleCount: 5,
lowLatency: 10,
collectCount: 5,
pingInterval: 10,
},
},
transporter: 'TCP',
};
const broker = new ServiceBroker(brokerConfig);
function genService(sSount, aCount) {
// create and attach some services
for (let i = 0; i < sSount; i += 1) {
const service = {
name: `service${i}`,
actions: {},
};
// create some actions on this service
for (let j = 0; j < aCount; j += 1) {
service.actions[`test${j}`] = {
handler: (ctx) => {
const { a, b } = ctx.params;
return a + b;
},
}
}
// attach service to broker
broker.createService(service);
}
}
genService(10, 10);
broker.start().catch(err => console.error(err));@zllovesuki I think that this is something related with your code. Could you take a look at this?
The MaxListenersExceededWarning seems to be caused by $node.latencySlave
https://github.com/moleculerjs/moleculer/blob/f2164f99ad2dbc057685e52aa8e646a5b476b869/src/strategies/latency.js#L78-L83
that's being called twice for each action (lines 33 and 43) https://github.com/moleculerjs/moleculer/blob/f2164f99ad2dbc057685e52aa8e646a5b476b869/src/registry/endpoint-list.js#L29-L44
so the localBus gets filled pretty fast
https://github.com/moleculerjs/moleculer/blob/f2164f99ad2dbc057685e52aa8e646a5b476b869/src/service-broker.js#L154-L158
For 10 nodes and 10 actions we have 212 $node.latencySlave listeners: 2 ($node.list + $node.services + $node.actions + $node.events + $node.health + $node.options + 10(nodes)10(actions))
zllovesuki
commented
5 years ago Ouch, that’s some bad stuff. Maybe only listen on actual actions instead of all. For now it is harmless, but I will take a look at it.
zllovesuki
commented
5 years ago IIRC each action gets its own registry, thus this was the unintended side effect.
zllovesuki
commented
4 years ago I wonder if the broker has a "master" bus?
icebob
commented
4 years ago There is a local bus for the core components via broker.localBus
zllovesuki
commented
4 years ago right, my code was listening on broker.localBus. However, I think my code added a listener for each action/service. Is there a way to share states internally? As I was noted in the code:
Since Strategy can be instantiated multiple times, therefore,
we need to have a "master" instance to send ping, and each
individual "slave" instance will update their list dynamically
Prerequisites
Please answer the following questions for yourself before submitting an issue.
Current Behavior
When using the latency strategy, node posts max event listeners error. When using other strategy, error does not happen. No obseverd negative side effects other than the console message. This seems to only happen when there are 3 or more mole nodes on the same service bus. The debug output is using the TCP transporter, but get the same error with MQTT transporter.
Expected Behavior
No error. :)
Failure Information
With
node --trace-warningsI get the following console messages (below).Steps to Reproduce
Please provide detailed steps for reproducing the issue.
Context
Please provide any relevant information about your setup. This is important in case the issue is not reproducible except for under certain conditions.
Failure Logs