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comparison: DebugClients/Python/coverage/multiproc.py
DebugClients/Python/coverage/multiproc.py
- changeset 6219
- d6c795b5ce33
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| 6218:bedab77d0fa3 | 6219:d6c795b5ce33 |
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| 1 # Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0 | |
| 2 # For details: https://bitbucket.org/ned/coveragepy/src/default/NOTICE.txt | |
| 3 | |
| 4 """Monkey-patching to add multiprocessing support for coverage.py""" | |
| 5 | |
| 6 import multiprocessing | |
| 7 import multiprocessing.process | |
| 8 import os | |
| 9 import sys | |
| 10 | |
| 11 from coverage.misc import contract | |
| 12 | |
| 13 # An attribute that will be set on the module to indicate that it has been | |
| 14 # monkey-patched. | |
| 15 PATCHED_MARKER = "_coverage$patched" | |
| 16 | |
| 17 # The environment variable that specifies the rcfile for subprocesses. | |
| 18 COVERAGE_RCFILE_ENV = "_COVERAGE_RCFILE" | |
| 19 | |
| 20 | |
| 21 if sys.version_info >= (3, 4): | |
| 22 OriginalProcess = multiprocessing.process.BaseProcess | |
| 23 else: | |
| 24 OriginalProcess = multiprocessing.Process | |
| 25 | |
| 26 original_bootstrap = OriginalProcess._bootstrap | |
| 27 | |
| 28 class ProcessWithCoverage(OriginalProcess): | |
| 29 """A replacement for multiprocess.Process that starts coverage.""" | |
| 30 | |
| 31 def _bootstrap(self): | |
| 32 """Wrapper around _bootstrap to start coverage.""" | |
| 33 from coverage import Coverage # avoid circular import | |
| 34 rcfile = os.environ[COVERAGE_RCFILE_ENV] | |
| 35 cov = Coverage(data_suffix=True, config_file=rcfile) | |
| 36 cov.start() | |
| 37 debug = cov.debug | |
| 38 try: | |
| 39 if debug.should("multiproc"): | |
| 40 debug.write("Calling multiprocessing bootstrap") | |
| 41 return original_bootstrap(self) | |
| 42 finally: | |
| 43 if debug.should("multiproc"): | |
| 44 debug.write("Finished multiprocessing bootstrap") | |
| 45 cov.stop() | |
| 46 cov.save() | |
| 47 if debug.should("multiproc"): | |
| 48 debug.write("Saved multiprocessing data") | |
| 49 | |
| 50 class Stowaway(object): | |
| 51 """An object to pickle, so when it is unpickled, it can apply the monkey-patch.""" | |
| 52 def __init__(self, rcfile): | |
| 53 self.rcfile = rcfile | |
| 54 | |
| 55 def __getstate__(self): | |
| 56 return {'rcfile': self.rcfile} | |
| 57 | |
| 58 def __setstate__(self, state): | |
| 59 patch_multiprocessing(state['rcfile']) | |
| 60 | |
| 61 | |
| 62 @contract(rcfile=str) | |
| 63 def patch_multiprocessing(rcfile): | |
| 64 """Monkey-patch the multiprocessing module. | |
| 65 | |
| 66 This enables coverage measurement of processes started by multiprocessing. | |
| 67 This involves aggressive monkey-patching. | |
| 68 | |
| 69 `rcfile` is the path to the rcfile being used. | |
| 70 | |
| 71 """ | |
| 72 | |
| 73 if hasattr(multiprocessing, PATCHED_MARKER): | |
| 74 return | |
| 75 | |
| 76 if sys.version_info >= (3, 4): | |
| 77 OriginalProcess._bootstrap = ProcessWithCoverage._bootstrap | |
| 78 else: | |
| 79 multiprocessing.Process = ProcessWithCoverage | |
| 80 | |
| 81 # Set the value in ProcessWithCoverage that will be pickled into the child | |
| 82 # process. | |
| 83 os.environ[COVERAGE_RCFILE_ENV] = rcfile | |
| 84 | |
| 85 # When spawning processes rather than forking them, we have no state in the | |
| 86 # new process. We sneak in there with a Stowaway: we stuff one of our own | |
| 87 # objects into the data that gets pickled and sent to the sub-process. When | |
| 88 # the Stowaway is unpickled, it's __setstate__ method is called, which | |
| 89 # re-applies the monkey-patch. | |
| 90 # Windows only spawns, so this is needed to keep Windows working. | |
| 91 try: | |
| 92 from multiprocessing import spawn | |
| 93 original_get_preparation_data = spawn.get_preparation_data | |
| 94 except (ImportError, AttributeError): | |
| 95 pass | |
| 96 else: | |
| 97 def get_preparation_data_with_stowaway(name): | |
| 98 """Get the original preparation data, and also insert our stowaway.""" | |
| 99 d = original_get_preparation_data(name) | |
| 100 d['stowaway'] = Stowaway(rcfile) | |
| 101 return d | |
| 102 | |
| 103 spawn.get_preparation_data = get_preparation_data_with_stowaway | |
| 104 | |
| 105 setattr(multiprocessing, PATCHED_MARKER, True) |
