1435270 - Log output sent to a file via MOZ_LOG_FILE is cut off

Status: NEW

(Core :: XPCOM, defect, P3)

Description

[Lennart Grahl [:lgrahl]]

Attachment: demo.html

When I use MOZ_LOG_FILE, log output sent to that file is apparently not flushed properly and cut off.

I'm setting the following environment variables:

export R_LOG_DESTINATION=stderr
export R_LOG_LEVEL=3
export R_LOG_VERBOSE=1
export MOZ_LOG=DataChannel:5,SCTP:3

Run the demo file and quit when it tells you to. The log output will probably end with something like:

[13948:Main Thread]: D/DataChannel 0x7f7479913060(0x7f747997f920): OnChannelClosed - Dispatching
[13948:Main Thread]: D/DataChannel 0x7f74799132e0(0x7f7479993450): OnChannelClosed - Dispatching

Now, run the demo with MOZ_LOG_FILE=/tmp/firefox.log and quit when it tells you to. For me, the log output is cut off:

[14370:Socket Thread]: D/DataChannel SendDeferredMessages called, pending type: 0
[14370:Socket Thread]: D/DataChannel SendDeferredMessages called, pending t

Tried with firefox-59.0b5

Comment 1

[Nathan Froyd [:froydnj]]

I'd guess there's some buffering involved when writing to a file, and that buffer doesn't get flushed if the browser exits.  Does MOZ_LOG=sync,DataChannel:5,SCTP:3 fix your problems?

Comment 2

[Lennart Grahl [:lgrahl]]

Yes, 'sync' helps.