view tests/basic_test_result.py @ 38732:be4984261611

merge: mark file gets as not thread safe (issue5933)

In default installs, this has the effect of disabling the thread-based
worker on Windows when manifesting files in the working directory. My
measurements have shown that with revlog-based repositories, Mercurial
spends a lot of CPU time in revlog code resolving file data. This ends
up incurring a lot of context switching across threads and slows down
`hg update` operations when going from an empty working directory to
the tip of the repo.

On mozilla-unified (246,351 files) on an i7-6700K (4+4 CPUs):

before: 487s wall
after:  360s wall (equivalent to worker.enabled=false)
cpus=2: 379s wall

Even with only 2 threads, the thread pool is still slower.

The introduction of the thread-based worker (02b36e860e0b) states that
it resulted in a "~50%" speedup for `hg sparse --enable-profile` and
`hg sparse --disable-profile`. This disagrees with my measurement
above. I theorize a few reasons for this:

1) Removal of files from the working directory is I/O - not CPU - bound
   and should benefit from a thread pool (unless I/O is insanely fast
   and the GIL release is near instantaneous). So tests like `hg sparse
   --enable-profile` may exercise deletion throughput and aren't good
   benchmarks for worker tasks that are CPU heavy.
2) The patch was authored by someone at Facebook. The results were
   likely measured against a repository using remotefilelog. And I
   believe that revision retrieval during working directory updates with
   remotefilelog will often use a remote store, thus being I/O and not
   CPU bound. This probably resulted in an overstated performance gain.

Since there appears to be a need to enable the thread-based worker with
some stores, I've made the flagging of file gets as thread safe
configurable. I've made it experimental because I don't want to formalize
a boolean flag for this option and because this attribute is best
captured against the store implementation. But we don't have a proper
store API for this yet. I'd rather cross this bridge later.

It is possible there are revlog-based repositories that do benefit from
a thread-based worker. I didn't do very comprehensive testing. If there
are, we may want to devise a more proper algorithm for whether to use
the thread-based worker, including possibly config options to limit the
number of threads to use. But until I see evidence that justifies
complexity, simplicity wins.

Differential Revision: https://phab.mercurial-scm.org/D3963

from __future__ import absolute_import, print_function

import unittest

class TestResult(unittest._TextTestResult):

    def __init__(self, options, *args, **kwargs):
        super(TestResult, self).__init__(*args, **kwargs)
        self._options = options

        # unittest.TestResult didn't have skipped until 2.7. We need to
        # polyfill it.
        self.skipped = []

        # We have a custom "ignored" result that isn't present in any Python
        # unittest implementation. It is very similar to skipped. It may make
        # sense to map it into skip some day.
        self.ignored = []

        self.times = []
        self._firststarttime = None
        # Data stored for the benefit of generating xunit reports.
        self.successes = []
        self.faildata = {}

    def addFailure(self, test, reason):
        print("FAILURE!", test, reason)

    def addSuccess(self, test):
        print("SUCCESS!", test)

    def addError(self, test, err):
        print("ERR!", test, err)

    # Polyfill.
    def addSkip(self, test, reason):
        print("SKIP!", test, reason)

    def addIgnore(self, test, reason):
        print("IGNORE!", test, reason)

    def onStart(self, test):
        print("ON_START!", test)

    def onEnd(self):
        print("ON_END!")

    def addOutputMismatch(self, test, ret, got, expected):
        return False

    def stopTest(self, test, interrupted=False):
        super(TestResult, self).stopTest(test)