diff options
| author |  Joey Hess <joeyh@joeyh.name> | 2016-04-18 14:04:20 -0400 |
|---|---|---|
| committer | Joey Hess <joeyh@joeyh.name> | 2016-04-18 14:04:50 -0400 |
| commit | 71f7e6a178b9b5e694975729f276548fc5461c21 (patch) | |
| tree | 6645ff0c45230878ed227f40fad5660ea87ed608 | |
| parent | c6d028f5e85e8cf3dcc2c15cf2e9d40a6ad16b81 (diff) | |
fix drop hang reported by musicmatze
Fix hang when dropping content needs to lock the content on a ssh remote,
which occurred when the remote has git-annex version 5.20151019 or newer.
Analysis: `race` runs 2 threads at once, and the hGetLine finishes first.
So, it tries to cancel the waitForProcess, but unfortunately that is making
a foreign call and so cannot be canceled. The remote git-annex-shell
is waiting for a line on stdin before it will exit. Deadlock.
This only occurred sometimes; I reproduced it going from darkstar to
elephant, but not from darkstar to darkstar. Not sure how that fits into
the above analysis -- perhaps a race condition is also involved?
Fixed by not using `race`; now the hGetLine will fail with an exception
if the remote git-annex-shell exits without any output.
| -rw-r--r-- | Remote/Git.hs | 21 | ||||
| -rw-r--r-- | debian/changelog | 4 |
2 files changed, 13 insertions, 12 deletions
diff --git a/Remote/Git.hs b/Remote/Git.hs index 256428137..284d6a49c 100644 --- a/Remote/Git.hs +++ b/Remote/Git.hs @@ -57,7 +57,6 @@ import Types.NumCopies import Control.Concurrent import Control.Concurrent.MSampleVar -import Control.Concurrent.Async import qualified Data.Map as M import Network.URI @@ -387,17 +386,14 @@ lockKey r key callback , std_out = CreatePipe , std_err = UseHandle nullh } - -- Wait for either the process to exit, or for it to - -- indicate the content is locked. - v <- liftIO $ race - (waitForProcess p) - (hGetLine hout) - let signaldone = void $ tryNonAsync $ liftIO $ do - hPutStrLn hout "" - hFlush hout - hClose hin - hClose hout - void $ waitForProcess p + v <- liftIO $ tryIO $ hGetLine hout + let signaldone = void $ tryNonAsync $ liftIO $ mapM_ tryNonAsync + [ hPutStrLn hout "" + , hFlush hout + , hClose hin + , hClose hout + , void $ waitForProcess p + ] let checkexited = not . isJust <$> getProcessExitCode p case v of Left _exited -> do @@ -405,6 +401,7 @@ lockKey r key callback liftIO $ do hClose hin hClose hout + void $ waitForProcess p failedlock Right l | l == Ssh.contentLockedMarker -> bracket_ diff --git a/debian/changelog b/debian/changelog index 588c34542..9c008669d 100644 --- a/debian/changelog +++ b/debian/changelog @@ -17,6 +17,10 @@ git-annex (6.20160413) UNRELEASED; urgency=medium * fsck: Warn when core.sharedRepository is set and an annex object file's write bit is not set and cannot be set due to the file being owned by a different user. + * Fix hang when dropping content needs to lock the content on a + ssh remote, which occurred when the remote has git-annex version + 5.20151019 or newer. (The bug was in the client side; the remote + git-annex-shell does not need to be upgraded.) -- Joey Hess <id@joeyh.name> Wed, 13 Apr 2016 13:30:32 -0400 |