Opened 10 years ago

Closed 10 years ago

#9057 closed defect (Fixed)

RemoteFile deadlock

Reported by: stuartm Owned by: stuartm
Priority: critical Milestone: 0.24
Component: MythTV - General Version: Master Head
Severity: medium Keywords:
Cc: Ticket locked: no

Description

I can reliably reproduce a deadlock in RemoteFile? if the connection/transfer is allowed to time out. In this case it does so because we're trying to play a recording from a drive which is in standby and is spinning up. 

2010-10-05 10:54:28.920 TV: Attempting to change from None to WatchingPreRecorded
2010-10-05 10:54:28.921 SendReceiveStringList(QUERY_CHECKFILE,0...) called from UI thread
2010-10-05 10:54:35.929 MythSocket(3fa5570:61): readStringList: Error, timed out after 7000 ms.
2010-10-05 10:54:35.929 RemoteFile::openSocket(file data socket), Error: Did not get proper response from 192.168.159.2:6543
2010-10-05 10:54:35.929 RemoteFile::openSocket(file data socket), Error: Failed to open socket, error was invalid response

Backtrace attached.

N.B. There appears to be a change of behaviour wrt to timeouts that probably deserves another ticket, we used to wait for the drive in the past.

Attachments (2)

backtrace.txt​ (15.0 KB) - added by stuartm 10 years ago.
Backtrace
remotefile_deadlock.diff​ (1.0 KB) - added by stuartm 10 years ago.
Possible fix

Download all attachments as: .zip

Change History (5)

Changed 10 years ago by stuartm

Attachment: backtrace.txt​ added

Backtrace

comment:1 Changed 10 years ago by stuartm

Owner: set to stuartm
Status: new → accepted

This one is pretty obvious, we call Close() in openSocket() if an error occurred, but Open() is still holding the lock which Close() requires.

Changed 10 years ago by stuartm

Attachment: remotefile_deadlock.diff​ added

Possible fix

comment:2 Changed 10 years ago by stuartm

Possible fix attached, needs to be reviewed by someone familiar with RemoteFile?.

comment:3 Changed 10 years ago by stuartm

Resolution: → Fixed
Status: accepted → closed

(In [26656]) Fix a frontend deadlock in the RemoteFile? socket code should we fail to open a socket successfully. This could be because the backend is waiting on a drive to spin up before responding which would exceed the 7 second timeout. Signed off by Chris Pinkham since he knows this code better than I do. Fixes #9057

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