Add Xvfb debugging code to run-webkit-tests.

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py

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 import logging
+import tempfile
 
 from webkitpy.layout_tests.breakpad.dump_reader_multipart import DumpReaderLinux
 from webkitpy.layout_tests.port import base
 from webkitpy.layout_tests.port import win
 
 
 _log = logging.getLogger(__name__)
 
 
 class LinuxPort(base.Port):
@@ skipping 20 matching lines @@
         super(LinuxPort, self).__init__(host, port_name, **kwargs)
         self._version = port_name[port_name.index('linux-') + len('linux-'):]
         self._architecture = 'x86_64'
         assert self._version in self.SUPPORTED_VERSIONS
 
         if not self.get_option('disable_breakpad'):
             self._dump_reader = DumpReaderLinux(host, self._build_path())
         self._original_home = None
         self._original_display = None
         self._xvfb_process = None
+        self._xvfb_stdout = None
+        self._xvfb_stderr = None
 
     def additional_driver_flag(self):
         flags = super(LinuxPort, self).additional_driver_flag()
         if not self.get_option('disable_breakpad'):
             flags += ['--enable-crash-reporter', '--crash-dumps-dir=%s' % self._dump_reader.crash_dumps_directory()]
         return flags
 
     def check_build(self, needs_http, printer):
         result = super(LinuxPort, self).check_build(needs_http, printer)
 
@@ skipping 66 matching lines @@
         self._filesystem.rmtree(dummy_home)
         self.host.environ['HOME'] = self._original_home
 
     def _start_xvfb(self):
         display = self._find_display()
         if not display:
             _log.warn('Failed to find a free display to start Xvfb.')
             return
 
         _log.info('Starting Xvfb with display "%s".', display)
+        self._xvfb_stdout = tempfile.NamedTemporaryFile(delete=False)
+        self._xvfb_stderr = tempfile.NamedTemporaryFile(delete=False)
         self._xvfb_process = self.host.executive.popen(
             ['Xvfb', display, '-screen', '0', '1280x800x24', '-ac', '-dpi', '96'],
-            stderr=self.host.executive.DEVNULL)
+            stdout=self._xvfb_stdout, stderr=self._xvfb_stderr)
 
         # By setting DISPLAY here, the individual worker processes will
         # get the right DISPLAY. Note, if this environment could be passed
         # when creating workers, then we wouldn't need to modify DISPLAY here.
         self._original_display = self.host.environ.get('DISPLAY')
         self.host.environ['DISPLAY'] = display
 
         # The poll() method will return None if the process has not terminated:
         # https://docs.python.org/2/library/subprocess.html#subprocess.Popen.poll
         if self._xvfb_process.poll() is not None:

[mithro, 2017/04/26 01:57:17]

Can you just call _stop_xvfb here? Or maybe share the code between the two
functions?

[Dirk Pranke, 2017/04/26 02:03:00]

Yeah, I should be able to refactor it.

             _log.warn('Failed to start Xvfb on display "%s."', display)
+            self._xvfb_stdout.close()
+            self._xvfb_stderr.close()
+            _log.warn('Xvfb stdout:\n%s', self.host.filesystem.read_text_file(self._xvfb_stdout.name))
+            _log.warn('Xvfb stderr:\n%s', self.host.filesystem.read_text_file(self._xvfb_stderr.name))
+            self.host.filesystem.remove(self._xvfb_stdout.name)
+            self.host.filesystem.remove(self._xvfb_stderr.name)
 
     def _find_display(self):
         """Tries to find a free X display, looping if necessary."""
         # The "xvfb-run" command uses :99 by default.
         for display_number in range(99, 120):
             display = ':%d' % display_number
             exit_code = self.host.executive.run_command(
                 ['xdpyinfo', '-display', display], return_exit_code=True)
             if exit_code == 1:
                 return display
         return None
 
     def _stop_xvfb(self):
         if self._original_display:
             self.host.environ['DISPLAY'] = self._original_display
+        if self._xvfb_stdout:
+            self._xvfb_stdout.close()
+        if self._xvfb_stderr:
+            self._xvfb_stderr.close()
         if not self._xvfb_process:
             return
         _log.debug('Killing Xvfb process pid %d.', self._xvfb_process.pid)
         self._xvfb_process.kill()
         self._xvfb_process.wait()
+        _log.warn('Xvfb stdout:\n%s', self.host.filesystem.read_text_file(self._xvfb_stdout.name))
+        _log.warn('Xvfb stderr:\n%s', self.host.filesystem.read_text_file(self._xvfb_stderr.name))
+        self.host.filesystem.remove(self._xvfb_stdout.name)
+        self.host.filesystem.remove(self._xvfb_stderr.name)
+
 
 
     def _path_to_driver(self, target=None):
         binary_name = self.driver_name()
         return self._build_path_with_target(target, binary_name)