worker: rewrite error handling so os._exit covers all cases
Previously the worker error handling is like:
pid = os.fork() --+
if pid == 0: |
.... | problematic
.... --+
try: --+
.... | worker error handling
--+
If a signal arrives when Python is executing the "problematic" lines, an
external error handling (dispatch.py) will take over the control flow and
it's no longer guaranteed "os._exit" is called (see
86cd09bc13ba for why it
is necessary).
This patch rewrites the error handling so it covers all possible code paths
for a worker even during fork.
Note: "os.getpid() == parentpid" is used to test if the process is parent or
not intentionally, instead of checking "pid", because "pid = os.fork()" may
be not atomic - it's possible that that a signal hits the worker before the
assignment completes [1]. The newly added test replaces "os.fork" to
exercise that extreme case.
[1]: CPython compiles "pid = os.fork()" to 2 byte codes: "CALL_FUNCTION" and
"STORE_FAST", so it's probably not atomic:
def f():
pid = os.fork()
dis.dis(f)
2 0 LOAD_GLOBAL 0 (os)
3 LOAD_ATTR 1 (fork)
6 CALL_FUNCTION 0
9 STORE_FAST 0 (pid)
12 LOAD_CONST 0 (None)
15 RETURN_VALUE
#require test-repo
Set vars:
$ . "$TESTDIR/helpers-testrepo.sh"
$ CONTRIBDIR="$TESTDIR/../contrib"
Prepare repo:
$ hg init
$ echo this is file a > a
$ hg add a
$ hg commit -m first
$ echo adding to file a >> a
$ hg commit -m second
$ echo adding more to file a >> a
$ hg commit -m third
$ hg up -r 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo merge-this >> a
$ hg commit -m merge-able
created new head
$ hg up -r 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
perfstatus
$ cat >> $HGRCPATH << EOF
> [extensions]
> perfstatusext=$CONTRIBDIR/perf.py
> [perf]
> presleep=0
> stub=on
> parentscount=1
> EOF
$ hg help perfstatusext
perfstatusext extension - helper extension to measure performance
list of commands:
perfaddremove
(no help text available)
perfancestors
(no help text available)
perfancestorset
(no help text available)
perfannotate (no help text available)
perfbdiff benchmark a bdiff between revisions
perfbranchmap
benchmark the update of a branchmap
perfcca (no help text available)
perfchangegroupchangelog
Benchmark producing a changelog group for a changegroup.
perfchangeset
(no help text available)
perfctxfiles (no help text available)
perfdiffwd Profile diff of working directory changes
perfdirfoldmap
(no help text available)
perfdirs (no help text available)
perfdirstate (no help text available)
perfdirstatedirs
(no help text available)
perfdirstatefoldmap
(no help text available)
perfdirstatewrite
(no help text available)
perffncacheencode
(no help text available)
perffncacheload
(no help text available)
perffncachewrite
(no help text available)
perfheads (no help text available)
perfindex (no help text available)
perfloadmarkers
benchmark the time to parse the on-disk markers for a repo
perflog (no help text available)
perflookup (no help text available)
perflrucachedict
(no help text available)
perfmanifest (no help text available)
perfmergecalculate
(no help text available)
perfmoonwalk benchmark walking the changelog backwards
perfnodelookup
(no help text available)
perfparents (no help text available)
perfpathcopies
(no help text available)
perfrawfiles (no help text available)
perfrevlog Benchmark reading a series of revisions from a revlog.
perfrevlogchunks
Benchmark operations on revlog chunks.
perfrevlogrevision
Benchmark obtaining a revlog revision.
perfrevrange (no help text available)
perfrevset benchmark the execution time of a revset
perfstartup (no help text available)
perfstatus (no help text available)
perftags (no help text available)
perftemplating
(no help text available)
perfvolatilesets
benchmark the computation of various volatile set
perfwalk (no help text available)
perfwrite microbenchmark ui.write
(use 'hg help -v perfstatusext' to show built-in aliases and global options)
$ hg perfaddremove
$ hg perfancestors
$ hg perfancestorset 2
$ hg perfannotate a
$ hg perfbdiff -c 1
$ hg perfbdiff --alldata 1
$ hg perfbranchmap
$ hg perfcca
$ hg perfchangegroupchangelog
$ hg perfchangeset 2
$ hg perfctxfiles 2
$ hg perfdiffwd
$ hg perfdirfoldmap
$ hg perfdirs
$ hg perfdirstate
$ hg perfdirstatedirs
$ hg perfdirstatefoldmap
$ hg perfdirstatewrite
$ hg perffncacheencode
$ hg perffncacheload
$ hg perffncachewrite
$ hg perfheads
$ hg perfindex
$ hg perfloadmarkers
$ hg perflog
$ hg perflookup 2
$ hg perflrucache
$ hg perfmanifest 2
$ hg perfmergecalculate -r 3
$ hg perfmoonwalk
$ hg perfnodelookup 2
$ hg perfpathcopies 1 2
$ hg perfrawfiles 2
$ hg perfrevlog .hg/store/data/a.i
$ hg perfrevlogrevision -m 0
$ hg perfrevlogchunks -c
$ hg perfrevrange
$ hg perfrevset 'all()'
$ hg perfstartup
$ hg perfstatus
$ hg perftags
$ hg perftemplating
$ hg perfvolatilesets
$ hg perfwalk
$ hg perfparents
Check perf.py for historical portability
$ cd "$TESTDIR/.."
$ (hg files -r 1.2 glob:mercurial/*.c glob:mercurial/*.py;
> hg files -r tip glob:mercurial/*.c glob:mercurial/*.py) |
> "$TESTDIR"/check-perf-code.py contrib/perf.py
contrib/perf.py:869:
> r.revision(r.node(x))
don't convert rev to node before passing to revision(nodeorrev)
[1]