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Joey Hess ed0afbc36b
avoid concurrent threads trying to take pid lock at same time 
Seem there are several races that happen when 2 threads run PidLock.tryLock
at the same time. One involves checkSaneLock of the side lock file, which may
be deleted by another process that is dropping the lock, causing checkSaneLock
to fail. And even with the deletion disabled, it can still fail, Probably due
to linkToLock failing when a second thread overwrites the lock file.

The same can happen when 2 processes do, but then one process just fails
to take the lock, which is fine. But with 2 threads, some actions where failing
even though the process as a whole had the pid lock held.

Utility.LockPool.PidLock already maintains a STM lock, and since it uses
LockShared, 2 threads can hold the pidlock at the same time, and when
the first thread drops the lock, it will remain held by the second
thread, and so the pid lock file should not get deleted until the last
thread to hold it drops the lock. Which is the right behavior, and why a
LockShared STM lock is used in the first place.

The problem is that each time it takes the STM lock, it then also calls
PidLock.tryLock. So that was getting called repeatedly and concurrently.

Fixed by noticing when the shared lock is already held, and stop calling
PidLock.tryLock again, just use the pid lock that already exists then.

Also, LockFile.PidLock.tryLock was deleting the pid lock when it failed
to take the lock, which was entirely wrong. It should only drop the side
lock.

Sponsored-by: Dartmouth College's Datalad project
2021-12-01 17:14:39 -04:00
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android
Android remove old android comments/bug reports 2021-06-21 13:21:27 -04:00
assistant
automatic_conflict_resolution
backends
bare_repositories
bugs avoid concurrent threads trying to take pid lock at same time 2021-12-01 17:14:39 -04:00
chunking
coding_style
contribute
copies
design document how to resume downloads 2021-10-11 12:40:16 -04:00
devblog comment 2021-11-09 16:04:54 -04:00
direct_mode
download
encryption
footer
forum Added a comment 2021-11-19 17:44:22 +00:00
future_proofing
git-annex-add
git-annex-addurl
git-annex-adjust
git-annex-checkpresentkey
git-annex-config
git-annex-copy
git-annex-direct
git-annex-drop
git-annex-enableremote
git-annex-find
git-annex-import
git-annex-importfeed
git-annex-lookupkey
git-annex-metadata
git-annex-move
git-annex-p2p
git-annex-preferred-content
git-annex-reinject
git-annex-rmurl
git-annex-setpresentkey
git-annex-sync
git-annex-test
git-annex-unannex
git-annex-undo
git-annex-uninit
git-annex-unlock
git-annex-unused
git-annex-whereis
how_it_works Added a comment 2021-08-18 21:07:12 +00:00
install remove xmpp mention 2021-10-19 12:26:22 -04:00
internals Added annex.freezecontent-command and annex.thawcontent-command configs 2021-06-21 14:40:52 -04:00
license
links
metadata
news add news item for git-annex 8.20211123 2021-11-23 15:20:58 -04:00
not
polls
preferred_content
profiling
projects collapse lists of done items by default 2021-11-16 12:38:41 -04:00
required_content
scalability
security
special_remotes When retrival from a chunked remote fails, display the error that occurred when downloading the chunk 2021-10-14 12:45:05 -04:00
stickers
submodules
sync
templates
testimonials
thanks update 2021-11-05 11:00:45 -04:00
tips Added a comment 2021-11-04 16:04:07 +00:00
todo comment 2021-12-01 13:03:05 -04:00
trust
tuning
upgrades
use_case
users removed 2021-11-04 16:06:17 +00:00
videos
walkthrough comment 2021-09-21 13:23:57 -04:00
workflow
Android.mdwn
assistant.mdwn
automatic_conflict_resolution.mdwn
backends.mdwn
bare_repositories.mdwn
bugs.mdwn fix name 2021-07-15 12:56:44 -04:00
builds.mdwn update for autobuilder changes 2021-07-02 13:03:19 -04:00
chunking.mdwn
coding_style.mdwn
comments.mdwn
contact.mdwn
contribute.mdwn
copies.mdwn
design.mdwn
devblog.mdwn
direct_mode.mdwn
distributed_version_control.mdwn
download.mdwn
encryption.mdwn
favicon.ico
forum.mdwn rename tag page 2021-07-15 12:55:05 -04:00
future_proofing.mdwn
git-annex-add.mdwn
git-annex-addunused.mdwn
git-annex-addurl.mdwn addurl, importfeed: Added --no-raw option 2021-06-27 11:14:51 -04:00
git-annex-adjust.mdwn improve docs 2021-11-12 14:08:36 -04:00
git-annex-assistant.mdwn
git-annex-benchmark.mdwn
git-annex-calckey.mdwn
git-annex-checkpresentkey.mdwn
git-annex-common-options.mdwn
git-annex-config.mdwn
git-annex-contentlocation.mdwn
git-annex-copy.mdwn --batch-keys 2021-08-25 14:21:12 -04:00
git-annex-dead.mdwn fix innacuracy 2021-06-25 14:48:36 -04:00
git-annex-describe.mdwn
git-annex-diffdriver.mdwn
git-annex-direct.mdwn
git-annex-drop.mdwn --batch-keys 2021-08-25 14:21:12 -04:00
git-annex-dropkey.mdwn
git-annex-dropunused.mdwn dropping unused marks as dead 2021-06-25 15:22:26 -04:00
git-annex-edit.mdwn
git-annex-enable-tor.mdwn
git-annex-enableremote.mdwn
git-annex-examinekey.mdwn
git-annex-expire.mdwn
git-annex-export.mdwn
git-annex-filter-branch.mdwn
git-annex-filter-process.mdwn add git-annex filter-process 2021-11-04 15:02:36 -04:00
git-annex-find.mdwn --batch-keys 2021-08-25 14:21:12 -04:00
git-annex-findref.mdwn
git-annex-fix.mdwn
git-annex-forget.mdwn
git-annex-fromkey.mdwn
git-annex-fsck.mdwn --batch-keys 2021-08-25 14:21:12 -04:00
git-annex-fuzztest.mdwn
git-annex-get.mdwn --batch-keys 2021-08-25 14:21:12 -04:00
git-annex-group.mdwn
git-annex-groupwanted.mdwn
git-annex-import.mdwn sync, merge: Added --allow-unrelated-histories option 2021-07-19 12:14:26 -04:00
git-annex-importfeed.mdwn addurl, importfeed: Added --no-raw option 2021-06-27 11:14:51 -04:00
git-annex-indirect.mdwn
git-annex-info.mdwn
git-annex-init.mdwn
git-annex-initremote.mdwn
git-annex-inprogress.mdwn note about encryption/chunking 2021-10-18 11:11:24 -04:00
git-annex-list.mdwn
git-annex-lock.mdwn
git-annex-log.mdwn --batch-keys 2021-08-25 14:21:12 -04:00
git-annex-lookupkey.mdwn
git-annex-map.mdwn
git-annex-matchexpression.mdwn
git-annex-matching-expression.mdwn
git-annex-matching-options.mdwn --batch-keys 2021-08-25 14:21:12 -04:00
git-annex-merge.mdwn sync, merge: Added --allow-unrelated-histories option 2021-07-19 12:14:26 -04:00
git-annex-metadata.mdwn metadata --batch: Avoid crashing when a non-annexed file is input 2021-11-01 13:40:43 -04:00
git-annex-migrate.mdwn migrate: New --remove-size option 2021-11-12 13:28:28 -04:00
git-annex-mincopies.mdwn
git-annex-mirror.mdwn --batch-keys 2021-08-25 14:21:12 -04:00
git-annex-move.mdwn --batch-keys 2021-08-25 14:21:12 -04:00
git-annex-multicast.mdwn
git-annex-numcopies.mdwn
git-annex-p2p.mdwn
git-annex-post-receive.mdwn
git-annex-pre-commit.mdwn
git-annex-preferred-content.mdwn
git-annex-proxy.mdwn
git-annex-readpresentkey.mdwn
git-annex-registerurl.mdwn
git-annex-reinit.mdwn
git-annex-reinject.mdwn
git-annex-rekey.mdwn migrate: New --remove-size option 2021-11-12 13:28:28 -04:00
git-annex-remotedaemon.mdwn
git-annex-renameremote.mdwn
git-annex-repair.mdwn
git-annex-required.mdwn
git-annex-resolvemerge.mdwn
git-annex-rmurl.mdwn
git-annex-schedule.mdwn
git-annex-semitrust.mdwn
git-annex-setkey.mdwn
git-annex-setpresentkey.mdwn
git-annex-shell.mdwn remove git-annex-shell compat code 2021-10-11 15:36:51 -04:00
git-annex-smudge.mdwn add git-annex filter-process 2021-11-04 15:02:36 -04:00
git-annex-status.mdwn
git-annex-sync.mdwn sync, merge: Added --allow-unrelated-histories option 2021-07-19 12:14:26 -04:00
git-annex-test.mdwn
git-annex-testremote.mdwn
git-annex-transferkey.mdwn
git-annex-transferkeys.mdwn
git-annex-transferrer.mdwn
git-annex-trust.mdwn
git-annex-unannex.mdwn
git-annex-undo.mdwn
git-annex-ungroup.mdwn
git-annex-uninit.mdwn
git-annex-unlock.mdwn
git-annex-unregisterurl.mdwn
git-annex-untrust.mdwn
git-annex-unused.mdwn improve docs for refspec format 2021-09-21 13:19:57 -04:00
git-annex-upgrade.mdwn
git-annex-vadd.mdwn
git-annex-vcycle.mdwn
git-annex-version.mdwn
git-annex-vfilter.mdwn
git-annex-vicfg.mdwn
git-annex-view.mdwn
git-annex-vpop.mdwn
git-annex-wanted.mdwn
git-annex-watch.mdwn
git-annex-webapp.mdwn
git-annex-whereis.mdwn --batch-keys 2021-08-25 14:21:12 -04:00
git-annex-whereused.mdwn wording 2021-07-14 17:08:38 -04:00
git-annex.mdwn add git-annex filter-process 2021-11-04 15:02:36 -04:00
git-remote-tor-annex.mdwn
git-union-merge.mdwn
how_it_works.mdwn
index.mdwn
install.mdwn
internals.mdwn
license.mdwn
location_tracking.mdwn
logo-old-bw.svg
logo-old.png
logo-old.svg
logo-old_small.png
logo.mdwn
logo.svg
logo_16x16.png
logo_32x32.png
logo_small.png
meta.mdwn
metadata.mdwn
news.mdwn
not.mdwn
polls.mdwn
preferred_content.mdwn
privacy.mdwn
profiling.mdwn
projects.mdwn
publicrepos.mdwn
related_software.mdwn
repomap.png
required_content.mdwn
scalability.mdwn
security.mdwn
shortcuts.mdwn
sidebar.mdwn
sitemap.mdwn
special_remotes.mdwn
stickers.mdwn
submodules.mdwn
summary.mdwn
sync.mdwn
testimonials.mdwn
thanks.mdwn
tips.mdwn
todo.mdwn
transferring_data.mdwn
trust.mdwn
tuning.mdwn
upgrades.mdwn
users.mdwn
videos.mdwn
walkthrough.mdwn
workflow.mdwn