I'll just make a few general style comments...
On Wed, Aug 12, 2009 at 7:04 PM, Lucas Meneghel Rodrigues<lmr@xxxxxxxxxx> wrote:
> This patch adds a system to watch user space segmentation
> faults, writing core dumps and some degree of core dump
> analysis report. We believe that such a system will be
> beneficial for autotest as a whole, since the ability to
> get core dumps and dump analysis for each app crashing
> during an autotest execution can help test engineers with
> richer debugging information.
>
> The system is comprised by 2 parts:
>
> * Modifications on test code that enable core dumps
> generation, register a core handler script in the kernel
> and check by generated core files at the end of each
> test.
>
> * A core handler script that is going to write the
> core on each test debug dir in a convenient way, with
> a report that currently is comprised by the process that
> died and a gdb stacktrace of the process. As the system
> gets in shape, we could add more scripts that can do
> fancier stuff (such as handlers that use frysk to get
> more info such as memory maps, provided that we have
> frysk installed in the machine).
>
> This is the proof of concept of the system. I am sending it
> to the mailing list on this early stage so I can get
> feedback on the feature. The system passes my basic
> tests:
>
> * Run a simple long test, such as the kvm test, and
> then crash an application while the test is running. I
> get reports generated on test.debugdir
>
> * Run a slightly more complex control file, with 3 parallel
> bonnie instances at once and crash an application while the
> test is running. I get reports generated on all
> test.debugdirs.
>
> But surely this has a long way to go before we can consider it
> for inclusion on autotest.
>
> Signed-off-by: Lucas Meneghel Rodrigues <lmr@xxxxxxxxxx>
> ---
> client/common_lib/test.py | 59 ++++++++++++-
> client/tools/crash_handler.py | 197 +++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 254 insertions(+), 2 deletions(-)
> create mode 100755 client/tools/crash_handler.py
>
> diff --git a/client/common_lib/test.py b/client/common_lib/test.py
> index 362c960..f519bfe 100644
> --- a/client/common_lib/test.py
> +++ b/client/common_lib/test.py
> @@ -17,7 +17,7 @@
> # tmpdir eg. tmp/<tempname>_<testname.tag>
>
> import fcntl, os, re, sys, shutil, tarfile, tempfile, time, traceback
> -import warnings, logging
> +import warnings, logging, glob
>
> from autotest_lib.client.common_lib import error
> from autotest_lib.client.bin import utils
> @@ -31,7 +31,6 @@ class base_test:
> self.job = job
> self.pkgmgr = job.pkgmgr
> self.autodir = job.autodir
> -
> self.outputdir = outputdir
> self.tagged_testname = os.path.basename(self.outputdir)
> self.resultsdir = os.path.join(self.outputdir, 'results')
> @@ -40,6 +39,7 @@ class base_test:
> os.mkdir(self.profdir)
> self.debugdir = os.path.join(self.outputdir, 'debug')
> os.mkdir(self.debugdir)
> + self.configure_crash_handler()
> self.bindir = bindir
> if hasattr(job, 'libdir'):
> self.libdir = job.libdir
> @@ -54,6 +54,45 @@ class base_test:
> self.after_iteration_hooks = []
>
>
> + def configure_crash_handler(self):
> + """
> + Configure the crash handler by:
> + * Setting up core size to unlimited
> + * Putting an appropriate crash handler on /proc/sys/kernel/core_pattern
> + * Create files that the crash handler will use to figure which tests
> + are active at a given moment
> +
> + The crash handler will pick up the core file and write it to
> + self.debugdir, and perform analysis on it to generate a report. The
> + program also outputs some results to syslog.
> +
> + If multiple tests are running, an attempt to verify if we still have
> + the old PID on the system process table to determine whether it is a
> + parent of the current test execution. If we can't determine it, the
> + core file and the report file will be copied to all test debug dirs.
> + """
> + self.pattern_file = '/proc/sys/kernel/core_pattern'
> + try:
> + # Trying to backup core pattern and register our script
> + self.core_pattern_backup = open(self.pattern_file, 'r').read()
> + pattern_fd = open(self.pattern_file, 'w')
I don't think it's a good idea to call file objects "fd". The os
module actually exposes methods for working directly with file
descriptors (which we use sometimes) so it can be confusing to read
code that refers to file objects as fd...part of my brain keeps
thinking "why isn't he using os.write if this is a file descriptor?"
> + tools_dir = os.path.join(self.autodir, 'tools')
> + crash_handler_path = os.path.join(tools_dir, 'crash_handler.py')
> + pattern_fd.write('|' + crash_handler_path + ' %p %t %u %s %h %e')
> + # Writing the files that the crash handler is going to use
> + self.debugdir_tmp_file = ('/tmp/autotest_results_dir.%s' %
> + os.getpid())
> + debugdir_fd = open(self.debugdir_tmp_file, 'w')
> + debugdir_fd.write(self.debugdir + "\n")
> + debugdir_fd.close()
There's actually a utils method for doing this cleanly called open_write_close.
> + # Now we can consider the system initialized.
> + self.crash_handling_enabled = True
> + logging.debug('Crash handling system enabled.')
Maybe this little snippet should be in an else clause, instead of
inside the try? Personally I think it makes it clearer to have "the
try part of the block didn't fail" in an else instead of at the end of
the try, and it has more symmetry with the except clause.
> + except Exception, e:
> + logging.debug('Crash handling system disabled: %s' % e)
> + self.crash_handling_enabled = False
I would set the flag before calling logging, like for the success
case. Also, you should pass e in as a parameter to debug rather than
doing the % formatting yourself.
Maybe that should also be logging.exception? Although that will raise
the visibility of the log, I suppose if you expect this to fail in
"normal" cases then that wouldn't be a good idea.
> +
> +
> def assert_(self, expr, msg='Assertion failed.'):
> if not expr:
> raise error.TestError(msg)
> @@ -403,6 +442,22 @@ class base_test:
> else:
> if self.network_destabilizing:
> self.job.enable_warnings("NETWORK")
> + # If core dumps are found on the debugdir after the execution of the
> + # test, let the user know.
> + if self.crash_handling_enabled:
> + core_dirs = glob.glob('%s/core.*' % self.debugdir)
> + if core_dirs:
> + logging.warning('Programs crashed during test execution:')
> + for dir in core_dirs:
> + logging.warning('Please verify %s for more info' % dir)
Again, pass in dir as a parameter to logging.warning, don't do %
formatting yourself.
> + # Remove the debugdir info file
> + os.unlink(self.debugdir_tmp_file)
> + # Restore the core pattern backup
> + try:
> + pattern_fd = open(self.pattern_file, 'w')
> + pattern_fd.write(self.core_pattern_backup)
> + except:
> + pass
I think open_write_close works here as well, although you'd still need
the try-except too.
Any reason you can't just go with a more specific exception type?
Maybe just catching EnvironmentError?
>
>
> def _get_nonstar_args(func):
> diff --git a/client/tools/crash_handler.py b/client/tools/crash_handler.py
> new file mode 100755
> index 0000000..a0d62a7
> --- /dev/null
> +++ b/client/tools/crash_handler.py
> @@ -0,0 +1,197 @@
> +#!/usr/bin/python
> +"""
> +Simple crash handling application for autotest
> +
> +@copyright Red Hat Inc 2009
> +@author Lucas Meneghel Rodrigues <lmr@xxxxxxxxxx>
> +"""
> +import sys, os, commands, glob, tempfile, shutil, syslog
> +
> +
> +def get_parent_pid(pid):
Personally, I think using /proc/$pid/stat would be nicer than calling ps.
> + """
> + Returns the parent PID for a given PID, converted to an integer.
> +
> + @param pid: Process ID.
> + """
> + try:
> + ppid = int(commands.getoutput("ps --pid=%s -o ppid=" % pid).split()[0])
> + except IndexError:
> + # It is not possible to determine the parent because the process
> + # already left the process table.
> + ppid = 1
> +
> + return ppid
> +
> +
> +def pid_descends_from(pid_a, pid_b):
> + """
> + Check whether pid_a descends from pid_b.
> +
> + @param pid_a: Process ID.
> + @param pid_b: Process ID.
> + """
> + pid_a = int(pid_a)
> + pid_b = int(pid_b)
> + current_pid = pid_a
> + while current_pid > 1:
> + if current_pid == pid_b:
> + syslog.syslog(syslog.LOG_INFO,
> + "PID %s descends from PID %s!" % (pid_a, pid_b))
> + return True
> + else:
> + current_pid = get_parent_pid(current_pid)
> + syslog.syslog(syslog.LOG_INFO,
> + "PID %s does not descend from PID %s" % (pid_a, pid_b))
> + return False
> +
> +
> +def write_to_file(file_path, contents):
I would steal the open_write_close implementation from the utils.
Although in practice it's not a big difference.
> + """
> + Write contents to a given file path specified. If not specified, the file
> + will be created.
> +
> + @param file_path: Path to a given file.
> + @param contents: File contents.
> + """
> + file_fd = open(file_path, 'w')
> + file_fd.write(contents)
> + file_fd.close()
> +
> +
> +def get_results_dir_list(pid, core_dir_basename):
> + """
> + Get all valid output directories for the core file and the report. It works
> + by inspecting files created by each test on /tmp and verifying if the
> + PID of the process that crashed is a child or grandchild of the autotest
> + test process. If it can't find any relationship (maybe a daemon that died
> + during a test execution), it will write the core file to the debug dirs
> + of all tests currently being executed. If there are no active autotest
> + tests at a particular moment, it will return a list with ['/tmp'].
> +
> + @param pid: PID for the process that generated the core
> + @param core_dir_basename: Basename for the directory that will hold both the
> + core dump and the crash report.
> + """
> + # Get all active test debugdir path files present
> + debugdir_files = glob.glob("/tmp/autotest_results_dir.*")
> + if debugdir_files:
> + pid_dir_dict = {}
> + for debugdir_file in debugdir_files:
> + a_pid = debugdir_file.split('.')[-1]
> + results_dir = open(debugdir_file, 'r').read().strip()
> + pid_dir_dict[a_pid] = os.path.join(results_dir, core_dir_basename)
> +
> + results_dir_list = []
> + found_relation = False
> + for a_pid in pid_dir_dict.keys():
for a_pid, a_path in pid_dir_dict.iteritems()
Then you don't need to do the lookup inside the if, you can just use a_path.
> + if pid_descends_from(pid, a_pid):
> + results_dir_list.append(pid_dir_dict[a_pid])
> + found_relation = True
> +
> + # If we could not find any relations between the pids in the list with
> + # the process that crashed, we can't tell for sure which tested spawned
> + # the process (maybe it is a daemon and started even before autotest
> + # started), so we will have to output the core file to all active test
> + # directories.
> + if not found_relation:
> + return [pid_dir_dict[d] for d in pid_dir_dict.keys()]
return pid_dir_dict.values()
> + else:
> + return results_dir_list
> +
> + else:
> + path_inactive_autotest = os.path.join('/tmp', core_dir_basename)
> + return [path_inactive_autotest]
> +
> +
> +def get_info_from_core(path):
> + """
> + Reads a core file and extracts a dictionary with useful core information.
> + Right now, the only information extracted is the full executable name.
> +
> + @param path: Path to core file.
> + """
> + # Here we are getting the executable full path in a very inelegant way :(
> + # Since the 'right' solution for it is to make a library to get information
> + # from core dump files, properly written, I'll leave this as it is for now.
> + full_exe_path = commands.getoutput('strings %s | grep "_="' %
> + path).strip("_=")
> + if full_exe_path.startswith("./"):
> + pwd = commands.getoutput('strings %s | grep "^PWD="' %
> + path).strip("PWD=")
> + full_exe_path = os.path.join(pwd, full_exe_path.strip("./"))
> +
> + return {'core_file': path, 'full_exe_path': full_exe_path}
> +
> +
> +if __name__ == "__main__":
> + syslog.openlog('AutotestCrashHandler', 0, syslog.LOG_DAEMON)
> + (crashed_pid, time, uid, signal, hostname, exe) = sys.argv[1:]
> + core_name = 'core'
> + report_name = 'report'
> + core_dir_name = 'crash.%s.%s' % (exe, crashed_pid)
> + core_tmp_dir = tempfile.mkdtemp(prefix='core_', dir='/tmp')
> + core_tmp_path = os.path.join(core_tmp_dir, core_name)
> + gdb_command_path = os.path.join(core_tmp_dir, 'gdb_command')
> +
> + # Get the filtered results dir list
> + current_results_dir_list = get_results_dir_list(crashed_pid, core_dir_name)
> +
> + # Write the core file to the appropriate directory
> + # (we are piping it to this script)
> + core_file = sys.stdin.read()
> + write_to_file(core_tmp_path, core_file)
> +
> + # Write a command file for GDB
> + gdb_command = 'bt full\n'
> + write_to_file(gdb_command_path, gdb_command)
> +
> + # Get full command path
> + exe_path = get_info_from_core(core_tmp_path)['full_exe_path']
> +
> + # Take a backtrace from the running program
> + gdb_cmd = 'gdb -e %s -c %s -x %s -n -batch -quiet' % (exe_path,
> + core_tmp_path,
> + gdb_command_path)
> + backtrace = commands.getoutput(gdb_cmd)
> + # Sanitize output before passing it to the report
> + backtrace = backtrace.decode('utf-8', 'ignore')
> +
> + # Composing the format_dict
> + format_dict = {}
> + format_dict['program'] = exe_path
> + format_dict['pid'] = crashed_pid
> + format_dict['signal'] = signal
> + format_dict['hostname'] = hostname
> + format_dict['time'] = time
> + format_dict['backtrace'] = backtrace
> +
> + report = """Autotest crash report
> +
> +Program: %(program)s
> +PID: %(pid)s
> +Signal: %(signal)s
> +Hostname: %(hostname)s
> +Time of the crash: %(time)s
> +Program backtrace:
> +%(backtrace)s
> +""" % format_dict
> +
> + syslog.syslog(syslog.LOG_INFO,
> + "Application %s, PID %s crashed" % (exe_path, crashed_pid))
> +
> + # Now, for all results dir, let's create the directory if it doesn't exist,
> + # and write the core file and the report to it.
> + syslog.syslog(syslog.LOG_INFO,
> + "Writing core files and reports to %s" %
> + current_results_dir_list)
> + for result_dir in current_results_dir_list:
> + if not os.path.isdir(result_dir):
> + os.makedirs(result_dir)
> + core_path = os.path.join(result_dir, 'core')
> + write_to_file(core_path, core_file)
> + report_path = os.path.join(result_dir, 'report')
> + write_to_file(report_path, report)
> + # Cleanup temporary directories
> + shutil.rmtree(core_tmp_dir)
Maybe this rmtree should be in a finally block; it's painful when
tmpdirs only get cleaned up when things succeed.
> +
> --
> 1.6.2.5
>
>
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