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

[Oleg Sukhodolsky]

+1 to Artem.

It is better to fix this too.

Oleg.

On Wed, Oct 26, 2011 at 7:34 PM, Artem Ananiev <artem.ananiev at oracle.com> wrote:
>
> 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;
>>>>> }
>>>>>
>>>>>
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