It is very hard to attach a debugger to WebProcess to debug tests

• Component: Tools / Tests
• Status: RESOLVED FIXED

[Alexey Proskuryakov]

When attaching a debugger to WebContent, one would normally hit a 5-second IPC timeout that WebKitTestRunner has. To safely debug, tests need to be run with something like:

run-webkit-tests --additional-drt-flag="--no-timeout-at-all" --time-out-ms=100000000

This is despite having a nice --no-timeout option in run-webkit-tests. This is because --no-timeout only affects waitUntilDone timeout, and not IPC timeout or run-webkit-tests timeout.

There is a claim (in <http://trac.webkit.org/changeset/123464>) that --no-timeout-at-all and --no-timeout needs to be different because of performance tests, but I don't see any evidence supporting that.

I want to make "run-webkit-tests --no-timeout" disable all timeouts, as best for debugging.

[Alexey Proskuryakov]

Created attachment 250937 [details]
proposed fix

[WebKit Commit Bot]

Attachment 250937 [details] did not pass style-queue:


ERROR: Tools/Scripts/webkitpy/port/driver.py:190:  at least two spaces before inline comment  [pep8/E261] [5]
Total errors found: 1 in 3 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Chris Dumez]

Comment on attachment 250937 [details]
proposed fix

r=me

[Geoffrey Garen]

Comment on attachment 250937 [details]
proposed fix

Maybe we should add a --debugger option, which auto-attaches a debugger after launching the Web Process, and also enables --no-timeout?

90% of the time, I would use that every time.

[Chris Dumez]

(In reply to comment #4)
> Comment on attachment 250937 [details]
> proposed fix
> 
> Maybe we should add a --debugger option, which auto-attaches a debugger
> after launching the Web Process, and also enables --no-timeout?
> 
> 90% of the time, I would use that every time.

FYI, back when I was working on the EFL port I added a specific run-webkit-test parameter exactly for this purpose: --webprocess-cmd-prefix

It is still in but the implementation probably needs to be adapted for Mac.

On EFL port it is used like so:
./Tools/Scripts/run-webkit-tests --efl --webprocess-cmd-prefix="DISPLAY=:0 xterm -title WebProcess -e gdb --eval-command=run --args" LayoutTests/fast/forms/plaintext-mode-1.html

[Alexey Proskuryakov]

> Maybe we should add a --debugger option, which auto-attaches a debugger after launching the Web Process, and also enables --no-timeout?

The --debugger option wouldn't know if I want to debug WebKitTestRunner, WebContent or Networking. And adding an option for each... I don't know, I just want to attach to the process in Xcode as it launches.

[Alexey Proskuryakov]

Committed r182916.