worker: manually buffer reads from pickle stream
My previous fix (D8051, cb52e619c99e, which added Python's built-in buffering
to the pickle stream) has the problem that the selector will ignore the buffer.
When multiple pickled objects are read from the pipe into the buffer at once,
only one object will be loaded.
This can repeat until the buffer is full and delays the processing of completed
items until the worker exits, at which point the pipe is always considered
readable and all remaining items are processed.
This changeset reverts D8051, removing the buffer again. Instead, on Python 3
only, we use a wrapper to modify the "read" provided to the Unpickler to behave
more like a buffered read. We never read more bytes from the pipe than the
Unpickler requests, so the selector behaves as expected.
Also add a test case for "pickle data was truncated" issue.
https://phab.mercurial-scm.org/D8051#119193
Differential Revision: https://phab.mercurial-scm.org/D8076
Test UI worker interaction
$ cat > t.py <<EOF
> from __future__ import absolute_import, print_function
> import sys
> import time
> from mercurial import (
> error,
> registrar,
> ui as uimod,
> worker,
> )
> sys.unraisablehook = lambda x: None
> def abort(ui, args):
> if args[0] == 0:
> # by first worker for test stability
> raise error.Abort(b'known exception')
> return runme(ui, [])
> def exc(ui, args):
> if args[0] == 0:
> # by first worker for test stability
> raise Exception('unknown exception')
> return runme(ui, [])
> def runme(ui, args):
> for arg in args:
> ui.status(b'run\n')
> yield 1, arg
> time.sleep(0.1) # easier to trigger killworkers code path
> functable = {
> b'abort': abort,
> b'exc': exc,
> b'runme': runme,
> }
> cmdtable = {}
> command = registrar.command(cmdtable)
> @command(b'test', [], b'hg test [COST] [FUNC]')
> def t(ui, repo, cost=1.0, func=b'runme'):
> cost = float(cost)
> func = functable[func]
> ui.status(b'start\n')
> runs = worker.worker(ui, cost, func, (ui,), range(8))
> for n, i in runs:
> pass
> ui.status(b'done\n')
> EOF
$ abspath=`pwd`/t.py
$ hg init
Run tests with worker enable by forcing a heigh cost
$ hg --config "extensions.t=$abspath" test 100000.0
start
run
run
run
run
run
run
run
run
done
Run tests without worker by forcing a low cost
$ hg --config "extensions.t=$abspath" test 0.0000001
start
run
run
run
run
run
run
run
run
done
#if no-windows
Known exception should be caught, but printed if --traceback is enabled
$ hg --config "extensions.t=$abspath" --config 'worker.numcpus=8' \
> test 100000.0 abort 2>&1
start
abort: known exception
[255]
$ hg --config "extensions.t=$abspath" --config 'worker.numcpus=8' \
> test 100000.0 abort --traceback 2>&1 | egrep '(SystemExit|Abort)'
raise error.Abort(b'known exception')
mercurial.error.Abort: known exception (py3 !)
Abort: known exception (no-py3 !)
SystemExit: 255
Traceback must be printed for unknown exceptions
$ hg --config "extensions.t=$abspath" --config 'worker.numcpus=8' \
> test 100000.0 exc 2>&1 | grep '^Exception'
Exception: unknown exception
Workers should not do cleanups in all cases
$ cat > $TESTTMP/detectcleanup.py <<EOF
> from __future__ import absolute_import
> import atexit
> import os
> import sys
> import time
> sys.unraisablehook = lambda x: None
> oldfork = os.fork
> count = 0
> parentpid = os.getpid()
> def delayedfork():
> global count
> count += 1
> pid = oldfork()
> # make it easier to test SIGTERM hitting other workers when they have
> # not set up error handling yet.
> if count > 1 and pid == 0:
> time.sleep(0.1)
> return pid
> os.fork = delayedfork
> def cleanup():
> if os.getpid() != parentpid:
> os.write(1, 'should never happen\n')
> atexit.register(cleanup)
> EOF
$ hg --config "extensions.t=$abspath" --config worker.numcpus=8 --config \
> "extensions.d=$TESTTMP/detectcleanup.py" test 100000 abort
start
abort: known exception
[255]
Do not crash on partially read result
$ cat > $TESTTMP/detecttruncated.py <<EOF
> from __future__ import absolute_import
> import os
> import sys
> import time
> sys.unraisablehook = lambda x: None
> oldwrite = os.write
> def splitwrite(fd, string):
> ret = oldwrite(fd, string[:9])
> if ret == 9:
> time.sleep(0.1)
> ret += oldwrite(fd, string[9:])
> return ret
> os.write = splitwrite
> EOF
$ hg --config "extensions.t=$abspath" --config worker.numcpus=8 --config \
> "extensions.d=$TESTTMP/detecttruncated.py" test 100000.0
start
run
run
run
run
run
run
run
run
done
#endif