<AWT Dev> sun.awt.X11.XEvent is creating 600 MB of char[] for no good reason

[Artem Ananiev]

On 10/26/2011 7:26 PM, Anthony Petrov wrote:
> On 10/26/2011 7:12 PM, Artem Ananiev wrote:
>> On 10/21/2011 4:00 PM, Anthony Petrov wrote:
>>> Indeed, this is a nasty issue. Thanks for spotting it. You may notice
>>> that in most other places where something is logged, the code usually
>>> checks whether logging is enabled for a certain level of logging, e.g.:
>>>
>>>> if (shapeLog.isLoggable(PlatformLogger.FINER)) {
>>>> shapeLog.finer(
>>>> "*** INFO: Setting shape: PEER: " + this
>>>> + "; WINDOW: " + getWindow()
>>>> + "; TARGET: " + target
>>>> + "; SHAPE: " + shape);
>>>> }
>>>
>>> So basically, we could simply wrap the line in question into a similar
>>> if(){} statement to make sure it gets executed only when the FINEST
>>> level of logging is enabled. A similar solution may also apply to
>>> another call to enableLog.finer() in the same method just a few lines
>>> below.
>>
>> Although the fix has been already pushed to the workspace, let me
>> wonder if, in addition to wrapping the logging calls with the "if ()"
>> checks, we should have also rewritten isEventDisabled() to use
>> StringBuilder?
>
> I guess you really mean the XEvent.getFieldsAsString() here [1], right?

Yes, exactly. Thanks for this correction.

> Possibly. But with Federico's fix this method now only gets called when
> logging is enabled, and as such the impact of the issue is limited.

I realize that. My point is that we just hide the problem, or make it 
less visible, or make it appear less frequently - whatever you prefer. 
However, the problematic code that contains char[] allocation is still 
in the workspace, and we know how often people use the current code as a 
pattern for future changes...

Thanks,

Artem

> [1] http://mail.openjdk.java.net/pipermail/awt-dev/2011-October/001952.html
>
> --
> best regards,
> Anthony
>
>
>>
>> Thanks,
>>
>> Artem
>>
>>> Could you make a patch, test it, and post it to this mailing list for
>>> review please?
>>>
>>> --
>>> best regards,
>>> Anthony
>>>
>>> On 10/21/2011 7:10 AM, Federico Tello Gentile wrote:
>>>> Hi.
>>>> I'm running
>>>>
>>>> java -version
>>>> java version "1.7.0_147-icedtea"
>>>> OpenJDK Runtime Environment (IcedTea7 2.0pre)
>>>> (7~b147-2.0~pre6-1ubuntu1)
>>>> OpenJDK 64-Bit Server VM (build 21.0-b17, mixed mode)
>>>>
>>>> and profiling a simple Swing application.
>>>>
>>>> Just by opening a JFrame and moving the mouse over it for 10 secods I
>>>> see 600 MB of char[] being created. I can easily create several
>>>> terabytes or those if I move the mouse a little longer. Thanks to the
>>>> incredibly efficient garbage collector the application performance is
>>>> not visibly affected on my 4GB quad core machine.
>>>>
>>>> The problem is an incredibly inefficient method
>>>> sun.awt.X11.XEvent.getFieldsAsString() which I pasted at the end of
>>>> this
>>>> message.
>>>>
>>>> The way it it handling string concatenation forces StringBuilder to
>>>> grow
>>>> many times and ends up calling Arrays.copyOf a lot of times.
>>>> It is being called by the sun.awt.X11.XWrapperBase.toString() just for
>>>> the sake of logging here:
>>>>
>>>> sun.awt.X11.XComponentPeer
>>>>
>>>> protected boolean isEventDisabled(XEvent e)
>>>>
>>>> enableLog.finest("Component is {1}, checking for disabled event
>>>> {0}", e,
>>>> (isEnabled()?"enabled":"disable"));
>>>>
>>>> The worse part is that even if logging is disabled and nothing at
>>>> all is
>>>> ever logged, the toString is called anyway and all those char[] are
>>>> created anyway.
>>>>
>>>> Here's a NetBeans profiler memory snapshot.
>>>>
>>>> http://ubuntuone.com/4xkprEzadUM4sUSdAnWlN5
>>>>
>>>>
>>>> This does not happen *at all* if I run the same profiling with this
>>>> openjdk version
>>>>
>>>> java -version
>>>> java version "1.6.0_23"
>>>> OpenJDK Runtime Environment (IcedTea6 1.11pre) (6b23~pre10-0ubuntu5)
>>>> OpenJDK 64-Bit Server VM (build 20.0-b11, mixed mode)
>>>>
>>>> I hope we can do something to improve this situation. I guess all Swing
>>>> applications are affected.
>>>>
>>>> I look forward for any comments.
>>>>
>>>> Here's the "thing"...
>>>>
>>>> ---------------------------------------------------
>>>>
>>>> String getFieldsAsString() {
>>>> String ret="";
>>>>
>>>> ret += ""+"type = " + XlibWrapper.eventToString[get_type()] +", ";
>>>> ret += ""+"xany = " + get_xany() +", ";
>>>> ret += ""+"xkey = " + get_xkey() +", ";
>>>> ret += ""+"xbutton = " + get_xbutton() +", ";
>>>> ret += ""+"xmotion = " + get_xmotion() +", ";
>>>> ret += ""+"xcrossing = " + get_xcrossing() +", ";
>>>> ret += ""+"xfocus = " + get_xfocus() +", ";
>>>> ret += ""+"xexpose = " + get_xexpose() +", ";
>>>> ret += ""+"xgraphicsexpose = " + get_xgraphicsexpose() +", ";
>>>> ret += ""+"xnoexpose = " + get_xnoexpose() +", ";
>>>> ret += ""+"xvisibility = " + get_xvisibility() +", ";
>>>> ret += ""+"xcreatewindow = " + get_xcreatewindow() +", ";
>>>> ret += ""+"xdestroywindow = " + get_xdestroywindow() +", ";
>>>> ret += ""+"xunmap = " + get_xunmap() +", ";
>>>> ret += ""+"xmap = " + get_xmap() +", ";
>>>> ret += ""+"xmaprequest = " + get_xmaprequest() +", ";
>>>> ret += ""+"xreparent = " + get_xreparent() +", ";
>>>> ret += ""+"xconfigure = " + get_xconfigure() +", ";
>>>> ret += ""+"xgravity = " + get_xgravity() +", ";
>>>> ret += ""+"xresizerequest = " + get_xresizerequest() +", ";
>>>> ret += ""+"xconfigurerequest = " + get_xconfigurerequest() +", ";
>>>> ret += ""+"xcirculate = " + get_xcirculate() +", ";
>>>> ret += ""+"xcirculaterequest = " + get_xcirculaterequest() +", ";
>>>> ret += ""+"xproperty = " + get_xproperty() +", ";
>>>> ret += ""+"xselectionclear = " + get_xselectionclear() +", ";
>>>> ret += ""+"xselectionrequest = " + get_xselectionrequest() +", ";
>>>> ret += ""+"xselection = " + get_xselection() +", ";
>>>> ret += ""+"xcolormap = " + get_xcolormap() +", ";
>>>> ret += ""+"xclient = " + get_xclient() +", ";
>>>> ret += ""+"xmapping = " + get_xmapping() +", ";
>>>> ret += ""+"xerror = " + get_xerror() +", ";
>>>> ret += ""+"xkeymap = " + get_xkeymap() +", ";
>>>> ret += "{" + get_pad(0) + " " + get_pad(1) + " " + get_pad(2) + " " +
>>>> get_pad(3) + " " + get_pad(4) + " " + get_pad(5) + " " + get_pad(6) + "
>>>> " + get_pad(7) + " " + get_pad(8) + " " + get_pad(9) + " " +
>>>> get_pad(10)
>>>> + " " + get_pad(11) + " " + get_pad(12) + " " + get_pad(13) + " " +
>>>> get_pad(14) + " " + get_pad(15) + " " + get_pad(16) + " " + get_pad(17)
>>>> + " " + get_pad(18) + " " + get_pad(19) + " " + get_pad(20) + " " +
>>>> get_pad(21) + " " + get_pad(22) + " " + get_pad(23) + " " + "}";
>>>> return ret;
>>>> }
>>>>
>>>>