[checkmk-commits] Fixed background job standard FD handling

Module: check_mk Branch: master Commit: 3c6485cc3a86ce6218bfc168b8f8924558c9d2b6 URL: http://git.mathias-kettner.de/git/?p=check_mk.git;a=commit;h=3c6485cc3a86ce… Author: Lars Michelsen <lm(a)mathias-kettner.de> Date: Tue Jul 24 20:27:56 2018 +0200 Fixed background job standard FD handling After each background job start these messages could be found in the apache error log: [Tue Jul 24 20:06:01.490903 2018] [wsgi:error] [pid 16596] [client 127.0.0.1:40244] close failed in file object destructor: [Tue Jul 24 20:06:01.490960 2018] [wsgi:error] [pid 16596] [client 127.0.0.1:40244] IOError: [Errno 9] Bad file descriptor This problem was caused by the handling of the open file descriptors when starting background job. During start all FDs except the first 3 were closed. The sys.stdout object was replaced in python with a StringIO() wrapper which is then used to collect the job results. But the FDs 0, 1 and 2 were not closed. To have a clean initial state we are now closing all FDs without exception. We proceed without stdin and also replace stderr with a stream wrapper that sends the written data to the var/log/web.log. Change-Id: I3596a793ac37d406b0aeded15cb5f6df922cee0b --- cmk/gui/background_job.py | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) diff --git a/cmk/gui/background_job.py b/cmk/gui/background_job.py index 96ab9ac..2c6daf7 100644 --- a/cmk/gui/background_job.py +++ b/cmk/gui/background_job.py @@ -194,14 +194,17 @@ class BackgroundProcess(multiprocessing.Process): except: MAXFD = 256 - # Close all filedescriptors, except stdin/stdout - os.closerange(3, MAXFD) + # Close all file descriptors + os.closerange(0, MAXFD) def initialize_environment(self): if not self._logger: self._logger = cmk.log.logger + sys.stderr = StreamLogger(self._logger, cmk.log.ERROR) + sys.stdout = StringIO() + self._job_parameters["logger"] = self._logger # Solely used for process identification @@ -211,7 +214,6 @@ class BackgroundProcess(multiprocessing.Process): def _execute_function(self): # The specific function is called in a separate thread # The main thread collects the stdout from the function-thread and updates the status file accordingly - sys.stdout = StringIO() t = threading.Thread(target=self._call_function_with_exception_handling, args=[self._job_parameters]) t.start() @@ -260,6 +262,27 @@ class BackgroundProcess(multiprocessing.Process): +# TODO(ab): Wouldn't it be better to also write the stderr to the job results instead of just writing +# it to the web.log? +class StreamLogger(object): + """File like stream object to redirects writes to the given logger""" + def __init__(self, logger, level): + super(StreamLogger, self).__init__() + self._logger = logger + self._level = level + self._linebuf = '' + + + def write(self, buf): + for line in buf.rstrip().splitlines(): + self._logger.log(self._level, line.rstrip()) + + + def flush(self): + pass + + + class BackgroundJobDefines(object): base_dir = os.path.join(cmk.paths.var_dir, "background_jobs") process_name = "cmk-job" # NOTE: keep this name short! psutil.Process tends to truncate long names