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

Wed Oct 26 13:14:46 PDT 2011

Yep, you are right. It is a WrapperGenerator who should be fixed.
And after that we need to regenerate all wrappers (if they are not
generated during build).

Oleg.

On Wed, Oct 26, 2011 at 11:27 PM, Federico <federicotg at gmail.com> wrote:
> Almost all sun.awt.X11.XWrapperBase subclasses have similarly horrible
> getFieldsAsString() implementations, but they are all automatically
> generated (which is a relief as there was no human being actually
> writing such code).
>
> They all say at the beginning:
>
> // This file is an automatically generated file, please do not edit
> this file, modify the WrapperGenerator.java file instead !
>
> My guess is in file
> /openjdk/jdk/src/solaris/classes/sun/awt/X11/generator/WrapperGenerator.java
>
> in line 678
> public void writeToString(StructType stp, PrintWriter pw) {
>
> starts the code generating bit.
>
>
> 2011/10/26 Oleg Sukhodolsky <son.two at gmail.com>:
>> +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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