Garbage Collector seems not to run

Hi!
I have a problem with the garbage collector:
To free memory, I regularly run the garbage collector in my app ( System.gc() ) after releasing resources by setting the reference variable to "null". But after some time I get an "out of heap memory" error. It seems that the gc doesn't run - I get the following result on the stdout:
0 garbage collections (0 bytes collected)
Is this possible? Or can I fix this problem?
Thanks for your help

Is it that the GC was not kicking-in even when you delete the references to the objects? That is true for any GC. GC will kick in only when you need more memory to create new objects
Also, you need to tune your young generation space and increase it from default 2MB to 32MB which will avoid frequent young generation GCs. By setting Xmx to 1024 MB, VM will try to grow till 1024 MB and if it can't allocate because
of less physical memory on your system, it will throw OutOfMemory errors.
I suggest you try the following:
1. Configure young generation to 32MB and old generation to 512 MB. This is how
you start your app
java -XX:MaxNewSize=32m -XX:NewSize=16m -Xms64m -Xmx512m -verbose:gc <app>
This sets the initial heap size to 64MB. You can increase this if your initial startup memory requirement (static memory) is higher that 64MB.
With Xmx set to 512MB, if some sessions die or are closed and heap size grows to 512MB, Full GC should kick in and you should be able to release memory for new sessions. Running with -verbose:gc will show if Full GC gets kicked in or not.
2. Try can calculate the static memory required at any point of time and also how much garbage is collected in certain time period. Then using these values we can make changes in young and old generation sizes.

Similar Messages

Garbage collector does not work any way

when you unload some loaded swf file (Loaded with Loader
class) it's Event Listeners continue their jobs
is there anyway to solve this problem
for example please made three files
l1.fla , l2.fla , main.fla
in l1 creat a MovieClip with instance name "symbol_mc"
and type these code
this.addEventListener(Event.ENTER_FRAME,test1,false,0,true);
function test1(evt:Event){
trace("l1");
symbol_mc.addEventListener(Event.ENTER_FRAME,test2,false,0,true);
function test2(evt:Event){
trace("symbol");
in l2 only create a text to see if file is loaded
finally in main
create to buttons with instance names btn1_btn and btn2_btn
and add these codes
var lo:Loader;
var mc:MovieClip = new MovieClip();
this.addChild(mc);
function loadSomeFile(url:String) {
lo= new Loader();
this.addChild(lo);
lo.contentLoaderInfo.addEventListener(Event.COMPLETE,
movieLoaded);
lo.load(new URLRequest(url));
function movieLoaded(evt:Event) {
this.removeChild(mc);
mc = MovieClip(lo.content);
this.removeChild(lo);
this.addChild(mc);
lo=null;
btn1_btn.addEventListener(MouseEvent.CLICK,load1);
function load1(evt:MouseEvent) {
loadSomeFile("l1.swf");
btn2_btn.addEventListener(MouseEvent.CLICK,load2);
function load2(evt:MouseEvent) {
loadSomeFile("l2.swf");
create swf files l1 and l2 and then preview main
first try btn1_btn and then try btn2_btn you will see after
unloading l1 and loading l2 event listeners will continue their
jobs!!!!!!!
after loading l1 ev

did you checked what you write in adobe devnet?
you said i must null loader but i not only did it but also
unloaded that before but event continue his life
i think it is not error of loader class it is gc error for
another example of it's errors try this create 2 frame fla file
add one symbole in frame 2 and then add event listener to
enterframe event of symbol
with two button add navigation for going to frames one and
two
you will see each time you enter frame 2 another
eventlistener will add to symbol and for example if your listener
rotate symbol by one degree you will see each time speed will
increase because each of them rotate object 1 degree

Strange garbage collector behaviour

Hello,
I am seeing quite a strange behaviour from the garbage collector in one of our applications.
The application is a standalone Java app, it receives requests over a TCP socket and responds to them. It is basically a kind of a cache before the database. There is a constant request flow of 10-100 requests per second. Average response time is below 50ms. It is running on a multiprocessor Sun machine, JDK 1.4.1_02.
The problem arises when the app has been running for a while. Depending on the allowed maximum memory size - with 256mb after about half a day, with 512mb after about a day, the garbage collector seems to be running most of the time. We turned on GC logging and from the log I can see that initially for a long period only the DefNew collector is used. The GC times are ~0.05sec then. Then after some time old generation collections start taking place. These collections take 3-4 seconds. The old gen collections then become more frequent until all that is going on, is one collection after another. About 3-4seconds for the collection, then after another 3-4 seconds the same thing again.
Can anyone please help in understanding what can cause this kind of behaviour? I am quite sure that the app is stable in a sense that it doesn't start to eat up extra memory at some point.
Any help greatly appreciated,
erik
Here are some excerpts from the GC log:
After startup:
100.264: [GC 100.264: [DefNew: 83488K->1290K(84800K), 0.0487560 secs] 87278K->5080K(259584K), 0.0490613 secs]
107.439: [GC 107.439: [DefNew: 83530K->1299K(84800K), 0.0526107 secs] 87320K->5178K(259584K), 0.0528313 secs]
111.554: [GC 111.554: [DefNew: 83539K->1207K(84800K), 0.0539021 secs] 87418K->5230K(259584K), 0.0541348 secs]
119.724: [GC 119.724: [DefNew: 83447K->1359K(84800K), 0.0561691 secs] 87470K->5382K(259584K), 0.0564463 secs]
125.576: [GC 125.576: [DefNew: 83599K->1366K(84800K), 0.0622342 secs] 87622K->5504K(259584K), 0.0624880 secs]
130.987: [GC 130.987: [DefNew: 83606K->1331K(84800K), 0.0586104 secs] 87744K->5607K(259584K), 0.0588732 secs]
138.695: [GC 138.695: [DefNew: 83571K->1296K(84800K), 0.0588720 secs] 87847K->5697K(259584K), 0.0591136 secs]
144.413: [GC 144.413: [DefNew: 83536K->1246K(84800K), 0.0607789 secs] 87937K->5790K(259584K), 0.0612128 secs]
150.661: [GC 150.661: [DefNew: 83486K->1279K(84800K), 0.0486299 secs] 88030K->5823K(259584K), 0.0488933 secs]
157.186: [GC 157.187: [DefNew: 83519K->1410K(84800K), 0.0545036 secs] 88063K->5954K(259584K), 0.0547557 secs]
162.937: [GC 162.937: [DefNew: 83650K->1230K(84800K), 0.0590144 secs] 88194K->5998K(259584K), 0.0592747 secs]
171.555: [GC 171.555: [DefNew: 83470K->1334K(84800K), 0.0554568 secs] 88238K->6101K(259584K), 0.0557090 secs]
175.416: [GC 175.416: [DefNew: 83574K->1315K(84800K), 0.0584964 secs] 88341K->6178K(259584K), 0.0587433 secs]
182.616: [GC 182.616: [DefNew: 83555K->1307K(84800K), 0.0709417 secs] 88418K->6234K(259584K), 0.0712034 secs]
And then in the end:
13177.7: [GC 13177.7: [DefNew: 82240K->82240K(84800K), 0.0000487 secs]13177.7: [Tenured: 95861K->96094K(174784K), 3.7160279 secs] 178101K->96094K(259584K), 3.7165109 secs]
13183.9: [GC 13183.9: [DefNew: 82240K->82240K(84800K), 0.0000459 secs]13183.9: [Tenured: 96094K->96268K(174784K), 3.6973634 secs] 178334K->96268K(259584K), 3.6978356 secs]
13193: [GC 13193: [DefNew: 82240K->82240K(84800K), 0.0000534 secs]13193: [Tenured: 96268K->95923K(174784K), 4.6233189 secs] 178508K->95923K(259584K), 4.6237995 secs]
13201.2: [GC 13201.2: [DefNew: 82240K->82240K(84800K), 0.0000531 secs]13201.2: [Tenured: 95923K->96100K(174784K), 3.7120306 secs] 178163K->96100K(259584K), 3.7125165 secs]
13208.6: [GC 13208.6: [DefNew: 82240K->82240K(84800K), 0.0000502 secs]13208.6: [Tenured: 96100K->96268K(174784K), 3.6950267 secs] 178340K->96268K(259584K), 3.6955072 secs]
13218.1: [GC 13218.1: [DefNew: 82240K->82240K(84800K), 0.0000582 secs]13218.1: [Tenured: 96268K->96442K(174784K), 3.7476890 secs] 178508K->96442K(259584K), 3.7481875 secs]
13225.8: [GC 13225.8: [DefNew: 82240K->82240K(84800K), 0.0002743 secs]13225.8: [Tenured: 96442K->96200K(174784K), 4.9092106 secs] 178682K->96200K(259584K), 4.9103437 secs]
13234.4: [GC 13234.4: [DefNew: 82240K->82240K(84800K), 0.0000541 secs]13234.4: [Tenured: 96200K->96409K(174784K), 3.7423712 secs] 178440K->96409K(259584K), 3.7428506 secs]
13240.6: [GC 13240.6: [DefNew: 82240K->82240K(84800K), 0.0000528 secs]13240.6: [Tenured: 96409K->96633K(174784K), 3.6245501 secs] 178649K->96633K(259584K), 3.6250124 secs]
13273.7: [GC 13273.7: [DefNew: 82240K->82240K(84800K), 0.0000651 secs]13273.7: [Tenured: 96633K->96799K(174784K), 3.7021988 secs] 178873K->96799K(259584K), 3.7027242 secs]
13283: [GC 13283: [DefNew: 82240K->82240K(84800K), 0.0000510 secs]13283: [Tenured: 96799K->96620K(174784K), 4.9944806 secs] 179039K->96620K(259584K), 4.9949444 secs]
I can provide the whole log if neccessary.

The most likely cause of this problem is a memory leak in your application. As the memory reaches close to its limit the GC has to run for longer, more often to get free memory.
The runtime before going slow being proportional to the memory size.
Can you have the program log the System.freeMemory() and System.totalMemory()

Garbage Collector Problems

Problem: The garbage collector on my server runs aprox every 1 min for
about 8 secs swamping the CPUs.
I started a not so big version of my "big server" using the following:
JDK 1.4
Windows NT 4.0
Compaq Proliant with 4 CPUs @ 800Mhz
4GB SDRAM
I am starting with the following parametrs:
-mx1536m -verbose:gc -XX:-DisableExplicitGC -Xrs
On start up, my server creates a lot of objects that will live forever. Over
time any time period only a few objects (in comparison) are created that
will die young. I assume that I want a large older generation and a smaller
young generation. I need enoug room in my older generation for my older
objects plus room for the minor collections since they use copy collection.
The verbose gc trace shows the collector running ~every min. Here is a snip
of the log:
17:35:57 | [Full GC 245559K->245496K(441840K), 8.2943686 secs]
17:36:35 | [Full GC 245577K->245507K(441840K), 8.2816641 secs]
17:37:13 | [Full GC 245588K->245526K(441840K), 8.3754267 secs]
17:37:52 | [Full GC 245617K->245554K(441840K), 8.2831863 secs]
17:38:30 | [Full GC 245635K->245573K(441840K), 8.2977681 secs]
I let the server run and there were hundres of these with never a minor gc.
My analysis (Are my assumtions correct?)
1. I do not see minor collections happening so I assume these full
collections are not caused by collection of the young generations.
2. Since during my test run I know that no one is hitting my server, there
should not be and are not and significant memory changes that would require
a minor collection (which is why I don't see them).
3. I am using Visobroker which, like RMI, may be making explicit gc calls.
To prevent this I tried calling -XX:+DisableExplicitGC yet the GC seems to
wants to run every minuite.
Is -XX:+DisableExplicitGC supported on JDK1.4 Win32?
Could something else be causing these Full GCs?
-Chris

I have one other suggestion, but it is a long shot. The total size of your heap is around 440M and the total in use is very close to 60% of that value.
Since the JVM by default tries will consider increasing the heap size (up to -Xmx) when the free space falls below 40% AFTER GC, perhaps it is GC-ing periodically because of that. This sounds stupid since it should adjust heap size because of GC, but it is worth a try.
You might consider this...
java -Xms440m -Xmx1536m -Xminf0.1 -Xmaxf0.9 ...
This will mean that the heap will only expand when you have less than 10% free and will contract only when you have more than 90% free, but only to value of -Xms.
You also might consider -Xincgc as well, which should eliminate the 8-second pauses in favor of a more distributed gc load. Since you are alrready getting hit by >10% GC overhead, this may give you overall greater throughput as well, but I wouldn't bet on it.
Are you using the -server JVM? If not, I'd switch to that as well.
Chuck

Garbage Collection is Not working

I Installed J2dk1.4 in my System.it's garbage Collector is not working,It does'nt free the memory in case of Frames and Applets.I use many methods to explicitly free the memory, Like :
====================
System.exit(0);
System.gc();
====================
but it does'nt work can any body give me the solution?
Email : [email protected]

How are you determining that it doesn't free memory?
If you're expecting Task Manager to show the VM using less memory, that won't happen. GC frees memory internally, so it can use that memory for other objects. It doesn't return it to the OS.
Also, calling gc() will not necessarily force the GC to run. Unless you're using a profiler, or getting OutOfMemoryError, you can't say for certain that the VM is not releasing memory.
Also, even if it's not releasing it, it doesn't mean it's a problem. It's guaranteed to release it when it needs it, but it may or may not release it sooner.
Finally, System.exit may not do anything in an applet, for security reasons.
What is your actual problem?

Help understand garbage collector behavour in case..

Here is the case:
class B{
// members and methods
class A{
B memberAB;
// other members and methods
class C{
B memberCB;
public void takeAndKeep_B()
A objA = new A();
memberCB = objA.memberAB;
//some code
// other members and methods
After takeAndKeep_B() finishes its job,
garbage collector will not release
memory occupied by objA
(because there is still a reference to it's member memberAB, I think)
Am I getting it right? Or the reason of memory leak is totaly unrelated to this case and I should look for it in some other place?
I would appreciate any oppinions so mush.

Here's how the garbage collector works: it collects any objects that the program cannot access. If an object cannot be accessed, it will be collected by the garbage collector if needed.
In your code, after takeAndKeep_B() finishes, there are no references to the new A object that the objA reference points to. Thus, the A object can be collected by the garbage collector.
Look at it this way: if the A class had a member named i that was an int, could your program access the i field of the A object you created after takeAndKeep_B() finishes? No, because the reference objA ceases to exist at the end of the method. Therefore, the object is unreachable and may be collected.
There is no way for an unreferenced object not to be collected by the garbage collector. Java cannot leak memory in this way.

GARBAGE COLLECTOR( NOT ACTIVATING)

I AM CERTIFIED, LEARNED IN THE COURSE THAT THE GARBAGE COLLECTOR IS A SYSTEM THREAD WHICH RUNS AND COLLECTS ALL THE UN-REFERENCED OBJECTS BUT I COULDN'T MANAGED TO ACTIVATE IT:
THE PROBLEM IS DEFINED AS FOLLOWS:-
1. WE KNOW THAT IF WE OVERRIDE THE FINALIZE METHOD OF AN OBJECT THEN IT IS CALLED WHEN THE SPECIFIC OBJECT IS GARBAGE COLLECTED.
THATS WHY I OVERRIDED A CLASS'S FINALIZE METHOD AND ISSUED A PRINTLN STATEMENT
2. THEN AT RUNTIME I INSTANTIATED THE OBJECT OF THAT PARTICULAR CLASS .
3. I SET THE REFERENCE TO NULL.( AT RUNTIME )
4. NOW ACCORDING TO THE DOCUMENTATION THE OBJECTED SHOULD BE GARBAGE COLLECTED AFTER SOMETIME BUT I WAITED FOR A ABOUT TEN MINUTES BUT IT ISN'T.
PLEASE ANSWER THIS QUESTION AN IF POSSIBLE EXPLAIN THE MECHANISM BY WHICH THE FINALIZE METHOD IS CALLED AT RUNTIME
IT SHOULD BE NOTED THAT THIS THREAD RUNS IN LOW MEMORY CONDITIONS BUT SINCE IT IS A LOW PRIORITY THREAD HOW CAN IT MANAGES TO RUN IN LOW MEMORY CONDITIONS

The only purpose finalize should be used for is a last ditch effort to free resources other than memory allocation. That said...
-It should NEVER be used to free a resource that is not automatically freed when the application exits. So for example it could be used to close a socket, but it should not exist when the 'resource' is a file.
-It should NEVER be the only way to free a resource. There is a reason I said "last ditch". The user of the object should have an explicit method to call which frees the resources.
And that said I would never use it regardless even for a last ditch cleanup. The reason for that is that it would tend to hide the improper usage of the class - in other words that the user wasn't calling the correct clean up method. I might use it to put a diagonistic (probably an unchecked exception) which indicates that the resource was not cleaned.
Expanding further on the other comments made here, if you read the spec you will find that the language does not guarantee that finalize will be called. All that it guarantees is that if it is called it will only be called once. In addition finalize can reduce performance because the existance of it might (and probably will) force the garbage collector to do two passes on the object rather than just one.

How to run garbage collector???????

I have to run garbage collector to enlarge totalmemory during runtime. I added code like System.gc( ), but it did nothing! the totalmemory stayed as before gc run.
anybody has idea or suggestion?
thanks a lot

Are you sure that there are no lingering references to
your objects. gc can only remove objects which have no
references to them remaining.No, this is not how garbage collection works in Java. Garbage collection collects unreachable objects, not objects with no references to them.
To understand the difference, look at this code:
Vector v = new Vector();
v.add(v);
v = new Vector();The original Vector object is unreachable at the end of this code, and is available for garbage collection. This is despite the fact that there exists a reference to the Vector, which is inside the Vector itself.
Some implementations of garbage collection, such as reference counting, really do collect only objects that have no references to them. Java's garbage collection is superior to these collectors: it collects all unreachable objects.

My G Drive will not show up on my desktop for use. It did yesterday. It is not full and currently the light turns on and seems to be running but will not show up on my desktop. What can I do?

My G Drive will not show up on my desktop for use. It did yesterday. It is not full and currently the light turns on and seems to be running but will not show up on my desktop. What can I do?

1. verify on another Mac first. and another port.
2. very likely dead SATA card
read about it here:
Your dead external hard drive is likely fine! Great hope for your 'faulty' external HD

Every time I try to install itunes on my PC I get the following message, and I can't seem to find a solution. Any help out there?? "There is a problem with this Windows Installer package. A program required for this install to complete could not be run."

Every time I try to install itunes on my PC I get the following message, and I can't seem to find a solution. Any help out there?? "There is a problem with this Windows Installer package. A program required for this install to complete could not be run."

Try the following user tip:
"There is a problem with this Windows Installer package ..." error messages when installing iTunes for Windows

[SOLVED!] KDE 4.11 - Window Manager seems not to be running?

Greetings,
I still seem unable to fix the fact that systemsettings will run. However it will run if you do kdesu systemsettings.
Doing so I started checking around in it and thought I'd look at the desktop effects, when I was greeted with this:
So, I am guessing that the window borders and buttons are a figment of my imagination....
This is after me pretty much starting over with KDE, removing the .kde and .kde4 folders.
Help?
Edit: That pic seems to not link right. Yay. Basically it says that effects can not be activated or whatever because a window manager seems not to be running. The irony of it is you can see the fact that there are window borders and buttons and such, evidence of a WM...
I wonder if there is something here that is related to me not being able to run systemsettings... yet systemsettings will run fine in any other environment - including Gnome Shell.
Another thing, KDE 4.11 ran great in testing and kde_unstable. Once it went to extra, things happened. I find that odd. Maybe something is missing on my end that most archers already have?
Edit2: fixed image link
Last edited by mythus (2013-08-25 20:49:38)

No omeringen, Nvidia user.
I can try again Thaodan since I've had some updates come through (and weeded out some dot files). Last time I tried I saw OpenGL 2 selected. Trying to change to 3 or anything else also got the screenshot in my OP.
I'll log into KDE and see if it still does the same, after a brief check for last minute updates.
EDIT: OK, so I can mark this as solved. I found an odd dot file, who's name excapes me but deals with kde sessions, just sitting around in the home folder. Once I deleted it and restarted, I found that not only System Settings finally ran again as a user, but I could also change and apply desktop effects. Peculiar. I thought that maybe it was a dot file that was causing the problem, that wasn't in the .kde or .kde4 folder. It just took finding it and removing it.
I wish I knew more to tell, but this at least solves my issue, and the issue with the non-running-as-user system settings I had posted in another thread (thinking that they were separate events. Thanks again for all your help guys!
Last edited by mythus (2013-08-25 20:49:05)

Is it possible to run garbage collector in publisher instance with out opening a tunnel?

Hi,
In General we are running garbage collector in publisher by opening a tunnel.
is there any alternate way to do that.
we installed adobe cq5 on solaris10.
thanks,
vidhyadhar

Check out - http://dev.day.com/docs/en/crx/current/administering/persistence_managers.html#Automating Garbage Collection
Example of curl command that will start up garbage collection. You can create a sheel script with the curl command and set it up to run as cron job on the publish server which should solve your problem.

My photoshop cs6 seems to be running very slow lately--not sure why? [was:question-please help]

My photoshop cs6 seems to be running very slow lately--not sure why?

Have you tried resetting your PRAM?
Shut the Mac down.
Holding the Cmd+Opt+P+R keys, press the power button.
Listen for the "startup chime" to sound three times and release the keys.
It should run better after it finishes booting up.

My interface -- buttons (back, forward, reload), firefox tab, groups, etc. -- does not look like the sample on your "firefox features" page. ("Groups" seems not to function at all.) I'm running the current firefox 4 download on Windows XP. Can you help?

My interface -- buttons (back, forward, reload), firefox tab, groups, etc. -- does not look like the sample on your "firefox features" page. ("Groups" seems not to function at all.) I'm running the current firefox 4 download on Windows XP. Can you help?

cor-el
Thank you for your swift reply. I don't know that this has helped me, as I've reached my level of tolerance for fooling with this annoying little problem - for today anyway. It has been going on since I "up" graded to Firefox 4. My wife is running 3.6.x on her laptop with none of this foolishness. As BLASPHEMOUS as it may sound, I've gone back to IE for the time being even though I don't like it 1000th as much as I do Firefox.
Not just to rant here, I would say that I found a way to put some buttons on the right side of the toolbar that immediately gave me permission to "back, forward, and reload", but upon closing the browser and going out for dinner with the wife, I find on return that not only are those buttons NOT still on the toolbar, but I can't find them anymore. I think they were in "add-ons" found under I believe Add-On Manager.
I did also manage to achieve back/forward functionality running Firefox in SAFE mode, but this meant no No-Script, among other things, and I've grown too fond of that particular little script to give it up.
I've rebooted, restored, and reinstalled, can't get this formerly completely reliable program to work like it always has. Before looking around on here, I was beginning to think it was my PC.
THANK YOU FOR YOUR HELP, cor-el. I'm going to see if I can get on live chat on Monday.
bossman344

Running garbage collector

How do I run the garbage collector to free memory and delete unused objects?

Maybe, I'm being stupid, but what has this got to do
with the garbage collector?The problem is that though you can make the garbage collector run, you can't easily tell it how hard or long to search for collectable objects. The GC makes several passes. First pass is a simply check that will collect only the most obviously collectable objects. So you can tell the gc to run, and it will, but it may miss a lot of the harder objects to collect. (Especially objects whos references are gone, but their location on the stack is active because of another method.)
So if we could tell the GC, run and don't come back till you get every last objects that is collectable, that would be an excellent thing!
In my experience, the GC is over agressive and will definitly collect any collectable objects when you manually run the gc.

Garbage Collector seems not to run

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