Opened 6 years ago

Closed 6 years ago

Last modified 6 years ago

#10647 closed Bug Report - Hang/Deadlock (fixed)

Scheduler deadlock during Live TV

Reported by: Jim Stichnoth Owned by: gigem
Priority: minor Milestone: 0.25.2
Component: MythTV - Scheduling Version: Master Head
Severity: medium Keywords:
Cc: Ticket locked: no

Description

While watching live TV, got the popup indicating that the backend wanted the tuner for a scheduled recording. I clicked "OK" to let the scheduled program record. This resulted in an apparent deadlock in the scheduler code. (To be precise, the scheduler wanted a different tuner but in the same input group as the Live TV tuner.) The deadlock manifested itself as mythfrontend and mythweb connection attempts hanging.

I attached gdb to the mythbackend process and got a stack trace.

Also including some backend logs with "-v most --loglevel debug". To make the size manageable, I filtered out lines containing "TFW" or "JobQueue?", and I removed lines prior to 1 minute before the recording. (But I kept the first 100 lines to show version and startup information.)

Attachments (2)

livetv_bt.txt (73.4 KB) - added by Jim Stichnoth 6 years ago.
mythbackend.log.gz (341.8 KB) - added by Jim Stichnoth 6 years ago.

Download all attachments as: .zip

Change History (7)

Changed 6 years ago by Jim Stichnoth

Attachment: livetv_bt.txt added

Changed 6 years ago by Jim Stichnoth

Attachment: mythbackend.log.gz added

comment:1 Changed 6 years ago by stuartm

Can you test the following patch? http://pastebin.ca/2162527

comment:2 Changed 6 years ago by David Engel <dengel@…>

Resolution: fixed
Status: newclosed

In ca273324961b95e300890ed40e833249b5460bd8/mythtv:

Hopefully remove more scheduler/recorder deadlocks.

Change the scheduler to unlock schedLock when calling the recorder
synchronously. If the recorder happens to be calling the scheduler at
the same time, this allows the recorder's call to grab the lock as
needed.

Fixes #10647, #10770 and #10771 .

comment:3 Changed 6 years ago by gigem

Milestone: unknown0.26

comment:4 Changed 6 years ago by David Engel <dengel@…>

In 4386e90e25ed40948bb208e8a325a8b072411e88/mythtv:

Hopefully remove more scheduler/recorder deadlocks.

Change the scheduler to unlock schedLock when calling the recorder
synchronously. If the recorder happens to be calling the scheduler at
the same time, this allows the recorder's call to grab the lock as
needed.

Refs #10647, #10770 and #10771 .
(cherry picked from commit ca273324961b95e300890ed40e833249b5460bd8)

Conflicts:

mythtv/programs/mythbackend/scheduler.cpp

comment:5 Changed 6 years ago by Kenni Lund [kenni a kelu dot dk]

Milestone: 0.260.25.2
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