[Bug threads/13251] New: frequent multithreading slows down GDB to the extent of making it unusable

[Bug threads/13251] New: frequent multithreading slows down GDB to the extent of making it unusable

[markus@hyperion-imrt.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=13251

             Bug #: 13251
           Summary: frequent multithreading slows down GDB to the extent
                    of making it unusable
           Product: gdb
           Version: 7.3
            Status: NEW
          Severity: critical
          Priority: P2
         Component: threads
        AssignedTo: unassigned@sourceware.org
        ReportedBy: markus@hyperion-imrt.org
    Classification: Unclassified


This is a follow-up on a bug that was submitted by me in Feb 2011 and never
resolved fully. I waited for 7.3 and it is still there.

The problem: the application program spawns a great many threads (in the
thousands, altogether) which each lives for a few ms. The threads are started
by boost::thread.

Each thread seems to allocate some memory in gdb which is never freed fully.
Further, the gdb process does something on a single CPU which grows longer in
time the more threads have been started (and stopped). With the growing
overhead
on a single CPU, performance drops rapidly. In the end, the process grinds to 
a halt, with GDB using all of one CPU´s capacity.

Following my first submission, I installed gdb-7.2.50-20110206 which was only a 
partial rememedy.

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[Bug threads/13251] frequent multithreading slows down GDB to the extent of making it unusable

[tromey at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13251

Tom Tromey <tromey at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at redhat dot com

--- Comment #1 from Tom Tromey <tromey at redhat dot com> 2011-11-09 20:36:21 UTC ---
(In reply to comment #0)
> This is a follow-up on a bug that was submitted by me in Feb 2011 and never
> resolved fully. I waited for 7.3 and it is still there.

Which PR is this?

> The problem: the application program spawns a great many threads (in the
> thousands, altogether) which each lives for a few ms. The threads are started
> by boost::thread.
> 
> Each thread seems to allocate some memory in gdb which is never freed fully.
> Further, the gdb process does something on a single CPU which grows longer in
> time the more threads have been started (and stopped). With the growing
> overhead
> on a single CPU, performance drops rapidly. In the end, the process grinds to 
> a halt, with GDB using all of one CPU´s capacity.

I wrote a simple program that has a loop creating and joining short-lived
(1 second) threads.  I ran this for quite some time but didn't see any
performance degradation or memory increase.

Do you have, or can you construct, a test case we can use?
The fewer dependencies the better.

What platform are you on?  I am using x86-64 Fedora 15.

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[Bug threads/13251] frequent multithreading slows down GDB to the extent of making it unusable

[tromey at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13251

Tom Tromey <tromey at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |WAITING

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[Bug threads/13251] frequent multithreading slows down GDB to the extent of making it unusable

[sergiodj at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=13251

Sergio Durigan Junior <sergiodj at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
                 CC|                            |sergiodj at redhat dot com
         Resolution|---                         |OBSOLETE

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