""" Overview ======== .. warning :: The multiprocess plugin is not available on Windows. The multiprocess plugin enables you to distribute your test run among a set of worker processes that run tests in parallel. This can speed up CPU-bound test runs (as long as the number of work processeses is around the number of processors or cores available), but is mainly useful for IO-bound tests that spend most of their time waiting for data to arrive from someplace else. .. note :: See :doc:`../doc_tests/test_multiprocess/multiprocess` for additional documentation and examples. Use of this plugin requires the multiprocessing_ module, also available from PyPI. .. _multiprocessing : http://code.google.com/p/python-multiprocessing/ How tests are distributed ========================= The ideal case would be to dispatch each test to a worker process separately. This ideal is not attainable in all cases, however, because many test suites depend on context (class, module or package) fixtures. The plugin can't know (unless you tell it -- see below!) if a context fixture can be called many times concurrently (is re-entrant), or if it can be shared among tests running in different processes. Therefore, if a context has fixtures, the default behavior is to dispatch the entire suite to a worker as a unit. Controlling distribution ^^^^^^^^^^^^^^^^^^^^^^^^ There are two context-level variables that you can use to control this default behavior. If a context's fixtures are re-entrant, set ``_multiprocess_can_split_ = True`` in the context, and the plugin will dispatch tests in suites bound to that context as if the context had no fixtures. This means that the fixtures will execute concurrently and multiple times, typically once per test. If a context's fixtures can be shared by tests running in different processes -- such as a package-level fixture that starts an external http server or initializes a shared database -- then set ``_multiprocess_shared_ = True`` in the context. These fixtures will then execute in the primary nose process, and tests in those contexts will be individually dispatched to run in parallel. How results are collected and reported ====================================== As each test or suite executes in a worker process, results (failures, errors, and specially handled exceptions like SkipTest) are collected in that process. When the worker process finishes, it returns results to the main nose process. There, any progress output is printed (dots!), and the results from the test run are combined into a consolidated result set. When results have been received for all dispatched tests, or all workers have died, the result summary is output as normal. Beware! ======= Not all test suites will benefit from, or even operate correctly using, this plugin. For example, CPU-bound tests will run more slowly if you don't have multiple processors. There are also some differences in plugin interactions and behaviors due to the way in which tests are dispatched and loaded. In general, test loading under this plugin operates as if it were always in directed mode instead of discovered mode. For instance, doctests in test modules will always be found when using this plugin with the doctest plugin. But the biggest issue you will face is probably concurrency. Unless you have kept your tests as religiously pure unit tests, with no side-effects, no ordering issues, and no external dependencies, chances are you will experience odd, intermittent and unexplainable failures and errors when using this plugin. This doesn't necessarily mean the plugin is broken; it may mean that your test suite is not safe for concurrency. """ import logging import os import sys import time import traceback import unittest import nose.case from nose.core import TextTestRunner from nose import failure from nose import loader from nose.plugins.base import Plugin from nose.result import TextTestResult from nose.suite import ContextSuite from nose.util import test_address from Queue import Empty from warnings import warn try: from cStringIO import StringIO except ImportError: import StringIO log = logging.getLogger(__name__) Process = Queue = Pool = Event = None def _import_mp(): global Process, Queue, Pool, Event if sys.platform == 'win32': warn("multiprocess plugin is not available on windows", RuntimeWarning) return try: from multiprocessing import Process as Process_, \ Queue as Queue_, Pool as Pool_, Event as Event_ Process, Queue, Pool, Event = Process_, Queue_, Pool_, Event_ except ImportError: warn("multiprocessing module is not available, multiprocess plugin " "cannot be used", RuntimeWarning) class TestLet: def __init__(self, case): try: self._id = case.id() except AttributeError: pass self._short_description = case.shortDescription() self._str = str(case) def id(self): return self._id def shortDescription(self): return self._short_description def __str__(self): return self._str class MultiProcess(Plugin): """ Run tests in multiple processes. Requires processing module. """ score = 1000 status = {} def options(self, parser, env): """ Register command-line options. """ if sys.platform == 'win32': return parser.add_option("--processes", action="store", default=env.get('NOSE_PROCESSES', 0), dest="multiprocess_workers", metavar="NUM", help="Spread test run among this many processes. " "Set a number equal to the number of processors " "or cores in your machine for best results. " "[NOSE_PROCESSES]") parser.add_option("--process-timeout", action="store", default=env.get('NOSE_PROCESS_TIMEOUT', 10), dest="multiprocess_timeout", metavar="SECONDS", help="Set timeout for return of results from each " "test runner process. [NOSE_PROCESS_TIMEOUT]") def configure(self, options, config): """ Configure plugin. """ if sys.platform == 'win32': return try: self.status.pop('active') except KeyError: pass if not hasattr(options, 'multiprocess_workers'): self.enabled = False return self.config = config try: workers = int(options.multiprocess_workers) except (TypeError, ValueError): workers = 0 if workers: _import_mp() if Process is None: self.enabled = False return self.enabled = True self.config.multiprocess_workers = workers self.config.multiprocess_timeout = int(options.multiprocess_timeout) self.status['active'] = True def prepareTestLoader(self, loader): """Remember loader class so MultiProcessTestRunner can instantiate the right loader. """ self.loaderClass = loader.__class__ def prepareTestRunner(self, runner): """Replace test runner with MultiProcessTestRunner. """ # replace with our runner class return MultiProcessTestRunner(stream=runner.stream, verbosity=self.config.verbosity, config=self.config, loaderClass=self.loaderClass) class MultiProcessTestRunner(TextTestRunner): def __init__(self, **kw): self.loaderClass = kw.pop('loaderClass', loader.defaultTestLoader) super(MultiProcessTestRunner, self).__init__(**kw) def run(self, test): """ Execute the test (which may be a test suite). If the test is a suite, distribute it out among as many processes as have been configured, at as fine a level as is possible given the context fixtures defined in the suite or any sub-suites. """ log.debug("%s.run(%s) (%s)", self, test, os.getpid()) wrapper = self.config.plugins.prepareTest(test) if wrapper is not None: test = wrapper # plugins can decorate or capture the output stream wrapped = self.config.plugins.setOutputStream(self.stream) if wrapped is not None: self.stream = wrapped testQueue = Queue() resultQueue = Queue() tasks = {} completed = {} workers = [] to_teardown = [] shouldStop = Event() result = self._makeResult() start = time.time() # dispatch and collect results # put indexes only on queue because tests aren't picklable for case in self.nextBatch(test): log.debug("Next batch %s (%s)", case, type(case)) if (isinstance(case, nose.case.Test) and isinstance(case.test, failure.Failure)): log.debug("Case is a Failure") case(result) # run here to capture the failure continue # handle shared fixtures if isinstance(case, ContextSuite) and self.sharedFixtures(case): log.debug("%s has shared fixtures", case) try: case.setUp() except (KeyboardInterrupt, SystemExit): raise except: log.debug("%s setup failed", sys.exc_info()) result.addError(case, sys.exc_info()) else: to_teardown.append(case) for _t in case: test_addr = self.address(_t) testQueue.put(test_addr, block=False) tasks[test_addr] = None log.debug("Queued shared-fixture test %s (%s) to %s", len(tasks), test_addr, testQueue) else: test_addr = self.address(case) testQueue.put(test_addr, block=False) tasks[test_addr] = None log.debug("Queued test %s (%s) to %s", len(tasks), test_addr, testQueue) log.debug("Starting %s workers", self.config.multiprocess_workers) for i in range(self.config.multiprocess_workers): p = Process(target=runner, args=(i, testQueue, resultQueue, shouldStop, self.loaderClass, result.__class__, self.config)) # p.setDaemon(True) p.start() workers.append(p) log.debug("Started worker process %s", i+1) num_tasks = len(tasks) while tasks: log.debug("Waiting for results (%s/%s tasks)", len(completed), num_tasks) try: addr, batch_result = resultQueue.get( timeout=self.config.multiprocess_timeout) log.debug('Results received for %s', addr) try: tasks.pop(addr) except KeyError: log.debug("Got result for unknown task? %s", addr) else: completed[addr] = batch_result self.consolidate(result, batch_result) if (self.config.stopOnError and not result.wasSuccessful()): # set the stop condition shouldStop.set() break except Empty: log.debug("Timed out with %s tasks pending", len(tasks)) any_alive = False for w in workers: if w.is_alive(): any_alive = True break if not any_alive: log.debug("All workers dead") break log.debug("Completed %s/%s tasks (%s remain)", len(completed), num_tasks, len(tasks)) for case in to_teardown: log.debug("Tearing down shared fixtures for %s", case) try: case.tearDown() except (KeyboardInterrupt, SystemExit): raise except: result.addError(case, sys.exc_info()) stop = time.time() result.printErrors() result.printSummary(start, stop) self.config.plugins.finalize(result) # Tell all workers to stop for w in workers: if w.is_alive(): testQueue.put('STOP', block=False) return result def address(self, case): if hasattr(case, 'address'): file, mod, call = case.address() elif hasattr(case, 'context'): file, mod, call = test_address(case.context) else: raise Exception("Unable to convert %s to address" % case) parts = [] if file is None: if mod is None: raise Exception("Unaddressable case %s" % case) else: parts.append(mod) else: parts.append(file) if call is not None: parts.append(call) return ':'.join(map(str, parts)) def nextBatch(self, test): # allows tests or suites to mark themselves as not safe # for multiprocess execution if hasattr(test, 'context'): if not getattr(test.context, '_multiprocess_', True): return if ((isinstance(test, ContextSuite) and test.hasFixtures(self.checkCanSplit)) or not getattr(test, 'can_split', True) or not isinstance(test, unittest.TestSuite)): # regular test case, or a suite with context fixtures # special case: when run like nosetests path/to/module.py # the top-level suite has only one item, and it shares # the same context as that item. In that case, we want the # item, not the top-level suite if isinstance(test, ContextSuite): contained = list(test) if (len(contained) == 1 and getattr(contained[0], 'context', None) == test.context): test = contained[0] yield test else: # Suite is without fixtures at this level; but it may have # fixtures at any deeper level, so we need to examine it all # the way down to the case level for case in test: for batch in self.nextBatch(case): yield batch def checkCanSplit(self, context, fixt): """ Callback that we use to check whether the fixtures found in a context or ancestor are ones we care about. Contexts can tell us that their fixtures are reentrant by setting _multiprocess_can_split_. So if we see that, we return False to disregard those fixtures. """ if not fixt: return False if getattr(context, '_multiprocess_can_split_', False): return False return True def sharedFixtures(self, case): context = getattr(case, 'context', None) if not context: return False return getattr(context, '_multiprocess_shared_', False) def consolidate(self, result, batch_result): log.debug("batch result is %s" , batch_result) try: output, testsRun, failures, errors, errorClasses = batch_result except ValueError: log.debug("result in unexpected format %s", batch_result) failure.Failure(*sys.exc_info())(result) return self.stream.write(output) result.testsRun += testsRun result.failures.extend(failures) result.errors.extend(errors) for key, (storage, label, isfail) in errorClasses.items(): if key not in result.errorClasses: # Ordinarily storage is result attribute # but it's only processed through the errorClasses # dict, so it's ok to fake it here result.errorClasses[key] = ([], label, isfail) mystorage, _junk, _junk = result.errorClasses[key] mystorage.extend(storage) log.debug("Ran %s tests (%s)", testsRun, result.testsRun) def runner(ix, testQueue, resultQueue, shouldStop, loaderClass, resultClass, config): log.debug("Worker %s executing", ix) loader = loaderClass(config=config) loader.suiteClass.suiteClass = NoSharedFixtureContextSuite def get(): case = testQueue.get(timeout=config.multiprocess_timeout) return case def makeResult(): stream = unittest._WritelnDecorator(StringIO()) result = resultClass(stream, descriptions=1, verbosity=config.verbosity, config=config) plug_result = config.plugins.prepareTestResult(result) if plug_result: return plug_result return result def batch(result): failures = [(TestLet(c), err) for c, err in result.failures] errors = [(TestLet(c), err) for c, err in result.errors] errorClasses = {} for key, (storage, label, isfail) in result.errorClasses.items(): errorClasses[key] = ([(TestLet(c), err) for c, err in storage], label, isfail) return ( result.stream.getvalue(), result.testsRun, failures, errors, errorClasses) try: try: for test_addr in iter(get, 'STOP'): if shouldStop.is_set(): break result = makeResult() test = loader.loadTestsFromNames([test_addr]) log.debug("Worker %s Test is %s (%s)", ix, test_addr, test) try: test(result) resultQueue.put((test_addr, batch(result))) except KeyboardInterrupt, SystemExit: raise except: log.exception("Error running test or returning results") failure.Failure(*sys.exc_info())(result) resultQueue.put((test_addr, batch(result))) except Empty: log.debug("Worker %s timed out waiting for tasks", ix) finally: testQueue.close() resultQueue.close() log.debug("Worker %s ending", ix) class NoSharedFixtureContextSuite(ContextSuite): """ Context suite that never fires shared fixtures. When a context sets _multiprocess_shared_, fixtures in that context are executed by the main process. Using this suite class prevents them from executing in the runner process as well. """ def setupContext(self, context): if getattr(context, '_multiprocess_shared_', False): return super(NoSharedFixtureContextSuite, self).setupContext(context) def teardownContext(self, context): if getattr(context, '_multiprocess_shared_', False): return super(NoSharedFixtureContextSuite, self).teardownContext(context)