Thomas Mahringer created TINKERPOP-2197:
-------------------------------------------
Summary: 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
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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