Bug 3915 - Memory leakage
Summary: Memory leakage
Alias: None
Product: frysk
Classification: Unclassified
Component: general (show other bugs)
Version: unspecified
: P2 normal
Target Milestone: ---
Assignee: Mike Cvet
Depends on: 4042
Blocks: 1633 3346
  Show dependency treegraph
Reported: 2007-01-24 15:53 UTC by Mike Cvet
Modified: 2007-02-27 18:20 UTC (History)
3 users (show)

See Also:
Last reconfirmed:

Screenshot of Gnome system monitor (12.74 KB, image/png)
2007-01-24 15:53 UTC, Mike Cvet
finalize() log file (64.41 KB, application/x-gzip)
2007-02-07 14:48 UTC, Mike Cvet

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Description Mike Cvet 2007-01-24 15:53:00 UTC
Opening on a sizeable program with debuginfo and source, and then attempting to 
step and run through it steadily increases the memory footprint of FryskGui.

Starting at around 100M on x86_64 when the SourceWindow first opens, and 
increasing around .5M per step.
Comment 1 Mike Cvet 2007-01-24 15:53:25 UTC
Created attachment 1519 [details]
Screenshot of Gnome system monitor
Comment 2 Rick Moseley 2007-02-02 21:34:53 UTC
Here are more observations on memory usage by the source window.  These results
were taken using "top" on a 2GHz P4 with 1GB of memory running FC5 with kernel
2.6.18-1.2257.fc5.  Of particular interest were the memory readings provided by
"top" for its Virtual, Resident and Shared columns.

The scenario is this:  I activated Frysk and took a measurement, then brought up
the source window and took a measurement and then stepped the program 10 times
taking two memory measurements after each step, with ~2 minutes between
measurements. An interesting phenomena was observed which is the reason 2
measurements were taken between each step.  It turns out there is a significance
difference between the virtual memory measurment right after the "step" and the
virtual memory measurement ~2 minutes after the step, which I suppose can be
attributed to GC(garbage collection).

The measurement taken immediately after the step was often 2-3 MB higher than
the measurement taken ~2 minutes later for the same step.  Here is a table of
the measurements:

   Virtual Memory        Resident     Shared
 after  ~2 min. later
 137MB     same             40          23       Initial startup of Frysk UI
 139MB     same             41          23       Showing debug process list
 155MB     152MB            44          25       Activated source window
 156MB     153MB            44          25       after 1 step
 158MB     155MB            45          25       after 2 steps
 160MB     157MB            45          25       after 3 steps
 161MB     158MB            45          25       after 4 steps       
 163MB     160MB            45          25       after 5 steps
 165MB     162MB            46          26       after 6 steps
 167MB     164MB            46          26       after 7 steps
 168MB     165MB            46          26       after 8 steps
 170MB     167MB            47          26       after 9 steps
 172MB     169MB            47          26       after 10 steps
 I also ran the test a different way by just doing 10 steps as quickly as I
could.  The initial virtual memory jumped to 192MB but fell back to 169MB within
2 minutes, the same as the memory measurement for step 10 above.
 Another phenomema I observed is that when the source window is exited, the
memory measured the last time stays the same, it does not go away unless all of
frysk is exited.  On top of that, if another source window is activated with the
same source code the memory useage jumps by another 4 MB over the last reading.
Comment 3 Mike Cvet 2007-02-07 14:48:41 UTC
Created attachment 1541 [details]
finalize() log file

A quick initial assessment shows that StackFrame.java, FrameCursor.java, and
the private class UnwindArgs in StackTraceCreator.java never seem to get
collected, while other objects associated with stepping do. 

The attached file is a log of finalize() calls from a variety of classes, some
from the DOM, Dwfl and DwflLine.

StackFrame is a pure Java file, FrameCursor and UnwindArgs have native
bindings; the DOM classes are pure Java and the Dwfl classes have native

Failure to reach the finalize() for UnwindArgs means that native clean-up
functions like unw_destroy_addr_space are not called.
Comment 4 Mike Cvet 2007-02-12 21:44:42 UTC
Looks like the TreeStore in CurrentStackView does not release any of the stored 
StackFrame objects contained in its rows after a call to TreeStore.clear(). 
Working up a standalone test for upstream java-gnome.
Comment 5 Mike Cvet 2007-02-13 21:24:50 UTC
Upstream bug:

Comment 6 Mike Cvet 2007-02-14 17:45:58 UTC
Well the story is that each time a step is performed, the stack trace gets re-
generated and the TreeView storing the stack trace in the source window needs 
to be refreshed with new StackFrame objects.

Due to the JG bug mentioned above, each time the tree is refreshed and 
(supposedly) cleared, the Java objects contained within are not marked for 
collection and get lost.

This is a serious problem since StackFrame objects are relatively heavy 
objects, with several heavy fields, such as DOMSource.

Nullifying references to all StackFrame fields each time the stack trace is 
rebuilt is a temporary workaround, but the problem really needs fixing in Java-

Suspending this bug until a fix for #4042 is created.
Comment 7 Mike Cvet 2007-02-27 18:20:13 UTC
Re: #4042, I've tested the patches Sami has made and they fix the problem.