Response larger than 4096 byte is not fully transmitted

[sunverwerth]

OS: Linux, 4.9.29
VSCode: 1.13.1
PHP Intellisense: 1.4.3

Links:
http://www.tldp.org/LDP/lpg/node13.html

This happens, for example, when I want to show symbols of a large file (ctrl+shift+o).
It also happens with other commands that return responses larger than 4kB.

Symptoms: Infinite loading bar. Hovering over a symbol while the loading bar is displayed finishes the request, as a new command is sent to the server and the remaining data is received.

It seems to be related to communication via stdio. Changing comms to socket fixes it.

I'm not sure if this is a vscode bug, but I'll be leaving this here and will investigate further.

Edit: When logging the fwrite return value in ProtocolStreamWriter and the chunk size received at the typescript site it looks something like this:

fwrite: 8000
client: 4096

Which means that php reports all bytes have been successfuly written and the remaining data must be stuck somewhere in the pipe. I suspect some kind of OS buffering issue.

[felixfbecker]

This is very good observation, thank you! I noticed sometimes symbol search just hangs and I never figured out why. Would be great if you could get to the bottom of this

[sunverwerth]

I also noticed another bug with similar symptoms that is caused by something else.
Sometimes the parser finishes but the indexes never reach their complete state.
The coroutines in Workspace and TextDocument then keep waiting for this event which never comes.

[sunverwerth]

Doesn't manifest on OSX

[sunverwerth]

I couldn't reproduce this bug on another linux machine. Only difference is the kernel version

[sunverwerth]

I couldn't reproduce this on any other computer. Maybe there is just something wrong with my system here.

[weirdan]

Adding 2048 as the third argument (limit) to the fwrite call in ProtocolStreamWriter fixed this problem for me. One would hardly call this elegant, but it works (for me).

[felixfbecker]

That could be a viable solution

[felixfbecker]

Btw, the issue could also be in the implementation of vscode-languageserver-node. NodeJS offers two stream APIs, one where you explicitly call read() to handle chunks, and one where you subscribe to the data event. data events are emitted when the buffer reaches highWaterMark.

[weirdan]

That could be a viable solution

Maybe it's not. It certainly helped somewhat, but I still observed some unfinished responses from time to time, even after adding fflush($this->output)

[sunverwerth]

Any news here? I am out of ideas as it only happens on one computer I tested on. Adding a setting to manually select sockets for communication could be a temporary workaround.

[felixfbecker]

How did you verify that the contents are not fully written out? Could you check that the stream actually does not send these bytes and it's not a NodeJS buffer issue?