[jira] [Commented] (TINKERPOP-2197) gremlin javascript - Error: read ECONNRESET at TLSWrap.onStreamRead - websocket error

["Thomas Mahringer (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TINKERPOP-2197?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16853794#comment-16853794 ] 

Thomas Mahringer commented on TINKERPOP-2197:
---------------------------------------------

Hi, thanks,

haven't had a chance to investigate it further so far.

I'm not sure how I can subscribe to the logs. I'm using azure Cosmos DB with the gremlin API.

Best

Thomas

> gremlin javascript - Error: read ECONNRESET  at TLSWrap.onStreamRead - websocket error
> --------------------------------------------------------------------------------------
>
>                 Key: TINKERPOP-2197
>                 URL: https://issues.apache.org/jira/browse/TINKERPOP-2197
>             Project: TinkerPop
>          Issue Type: Bug
>          Components: driver, javascript
>    Affects Versions: 3.4.0
>         Environment: windows 10 ent, 10.016299
> nodejs 11.10.1
> gemlin javascript 3.4.0
> express 4.16.4
>            Reporter: Thomas Mahringer
>            Priority: Major
>         Attachments: gremlin-ws-error.png
>
>
> *Environment*
>  
> I'm running a nodejs express app and connect to MSFT azure gremlin through the js driver:
>  
> {code:java}
> connect() {
>  this.authenticator = new     
>   Gremlin.driver.auth.PlainTextSaslAuthenticator(
>   `/dbs/${this.config.database}/colls/${this.config.collection}`,  
>    this.config.primaryKey)
>    this.client = new Gremlin.driver.Client(
>      this.config.endpoint,
>      { 
>        authenticator: this.authenticator, 
>        traversalsource: "g", 
>        rejectUnauthorized: true, 
>        mimeType: "application/vnd.gremlin-v2.0+json" 
>     }
> }
> );
> {code}
>  
>  
> The app calls various gremlin commands through the string + "query parameter" syntax, e.g. 
> {code:java}
> await this.client.submit("g.V().hasLabel(label)", {label: "Person"});{code}
>  
> All the queries work fine but when the app is idling for about 5-10 minutes, the nodejs process exits with the above error. None of my error handlers are hit. 
> So I debugged the gremlin js code and found out where the error is thrown: 
> It's the error handler in gremlin/lib/driver/connection.js, which gets installed in "open"
> {code:java}
> open() {
>   if (this.isOpen) {
>     return Promise.resolve();
>   }
>   if (this._openPromise) {
>     return this._openPromise;
>   }
>   this.emit('log', `ws open`);
>   this._ws = new WebSocket(this.url, {
>     headers: this.options.headers,
>     ca: this.options.ca,
>     cert: this.options.cert,
>     pfx: this.options.pfx,
>     rejectUnauthorized: this.options.rejectUnauthorized
>   });
>   this._ws.on('message', (data) => this._handleMessage(data));
>   // ******* Install error handler
>   this._ws.on('error', (err) => this._handleError(err));
> ...
> }
> _handleError(err) {
>  this.emit('log', `ws error ${err}`);
>  console.error("***************** Added log to improve debug ****************")
>  this._cleanupWebsocket();
>  this.emit('error', err); // Error ist thrown here
> }{code}
>  
> In the debugger I can see that the error is caused in *stream_base_commons.js:*
> {code:java}
> function onStreamRead(arrayBuffer) {
>  const nread = streamBaseState[kReadBytesOrError];
>  const handle = this;
>  const stream = this[owner_symbol];
>  stream[kUpdateTimer]();
>  if (nread > 0 && !stream.destroyed) {
>    const offset = streamBaseState[kArrayBufferOffset];
>    const buf = new FastBuffer(arrayBuffer, offset, nread);
>    if (!stream.push(buf)) {
>      handle.reading = false;
>      if (!stream.destroyed) {
>        const err = handle.readStop();
>        if (err)
>          stream.destroy(errnoException(err, 'read'));
>      }
>    }
>    return;
>  }
>  if (nread === 0) {
>    return;
>  }
>  if (nread !== UV_EOF) {
>    /*Happens here >>>> */ return stream.destroy(errnoException(nread, 'read'));
>  }
> ...
> }
> {code}
>  
> So my questions are:
>  * Why is the error thrown in the first place. (After app idles for 5-10 minutes)
>  ** What happens in "this.emit('error', err);" in "Connection._handleError".
>  * What is the right place to catch the error? I've of course wrapped the "submit" code above in try/catch (in case of async/await) or as "then(...).catch()..." (in case of using the promise directly). Since the error causes nodejs to exit, it's quite bad.:) 
>  ** As it all happens asynchronously, I would need something like an "onError" handler. But the web socket and its handler (this._ws.on('error')...) are within the  "Connection" class.
> The attached image shows the stack trace in Visual Studio Code Debugger.
> Any help is appreciated!
> Thanks
> Thomas 



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