Unclosed streams caused FS error after calling jq.json 2048 times.

[zhangweis]

I've got FS error after 2048 times calling jq.json.
I debugged and found unclosed streams in FS.streams caused by https://github.com/fiatjaf/jq-web/blob/master/post.js#L20.
Below code can show the error.

jq.onInitialized.addListener(()=>{
    for (var i =0;i<4098;i++) {
        console.log(jq.json({ok:i},'.'));
    }
    console.log('ok')
})

You'll get
...
{ ok: 2046 }
Error: FS error
Error: FS error
..../jq.asm.bundle1.js:122
throw ex
^

Error: abort(Error: FS error). Build with -s ASSERTIONS=1 for more info.

[fiatjaf]

Do you know how to fix it?
Just calling FS.close on these streams?

[zhangweis]

I've tried commenting the 2 lines and seems no negative impacts happened. Is it for large content or something?

[fiatjaf]

I don't remember. All I have are the same hints you do:

jq-web/post.js

Lines 17 to 21 in cf1752c

	Module.callMain(flags.concat(filter))
	// calling main closes stdout, so we reopen it here:
	FS.streams[1] = FS.open('/dev/stdout', 577, 0)
	FS.streams[2] = FS.open('/dev/stderr', 577, 0)

"calling main closes stdout, so we reopen here".

Maybe this means the negative impacts would only be felt in the second run?
Or maybe this was an emscripten bug that was fixed already, so main isn't closing the streams anymore as it did before, that's why they're being kept open now and causing issues.

[zhangweis]

I'm using a fix like below and so far it works for me.

        var stream1,stream2;
        stream1=FS.open("/dev/stdout",577,0);stream2=FS.open("/dev/stderr",577,0);
        setTimeout(()=>{FS.close(stream1);FS.close(stream2);},10000);