Daniel, could you please sponsor this fix?
Mattias
----- Original Message -----
From: daniel.fu...@oracle.com
To: mattias.tobias...@oracle.com, shanliang.ji...@oracle.com
Cc: serviceability-dev@openjdk.java.net
Sent: Friday, February 28, 2014 12:05:47 PM GMT +01:00 Amsterdam / Berlin /
Bern / Rome / Stockholm / Vienna
Subject: Re: RFR(XS) 8031065: LowMemoryTest2.sh fails: OutOfMemoryError:
Metaspace
Hi Mattias,
The new version looks good!
best regards,
-- daniel
On 2/28/14 11:33 AM, Mattias Tobiasson wrote:
> Hi,
> I have updated the test and now stop allocating when we have reached the
> threshold.
> Since we now do all allocations first and then just wait for the
> notification, I have split the loop into two separate loops to make it
> clearer.
>
> To detect if we have reached the threshold I now check
> MemoryPoolMXBean.getUsageThresholdCount() > 0 instead of checking
> isUsageThresholdExceeded().
> The reason for that is because the notification event is not generated
> immediately when isUsageThresholdExceeded() = true. The notification is only
> generated at the next GC. So that is the reason for why the old test kept
> allocating after it had reached the threshold (to trigger another GC).
>
> getUsageThresholdCount() is updated at the same time as the event is
> generated. So after getUsageThresholdCount() > 0, I can just wait for the
> notification without more allocations.
>
> webrev:
> http://cr.openjdk.java.net/~mtobiass/8031065/webrev.01
>
> bug:
> https://bugs.openjdk.java.net/browse/JDK-8031065
>
> Mattias
>
> ----- Original Message -----
> From: shanliang.ji...@oracle.com
> To: mattias.tobias...@oracle.com
> Cc: serviceability-dev@openjdk.java.net, daniel.fu...@oracle.com
> Sent: Thursday, February 27, 2014 5:12:51 PM GMT +01:00 Amsterdam / Berlin /
> Bern / Rome / Stockholm / Vienna
> Subject: Re: RFR(XS) 8031065: LowMemoryTest2.sh fails: OutOfMemoryError:
> Metaspace
>
>
> Mattias Tobiasson wrote:
>
> Hi, thanks for the fast reviews.
>
> I did think about stop calling loadNext() after the flag has been set. The
> main reason for not doing that was just because I wanted to change as little
> as possible. Now the test works as originally intended. I prefer to do like
> this too :)
>
>
> I do not mind removing the calls to loadNext(), but then we would need some
> timeout waiting for the callback. Currently the test "times out" with an
> OutOfMemory when we have allocated the remaining 20% of the space. You do not
> need to add a timeout, only change Line 151
> for(;;)
> to
> while(!listenerInvoked) {
>
> and remove 160 -- 162
>
> in case that an expected notification is not arrived, the testing harness has
> a timeout to stop the test.
>
> This way makes the test more robust, but I am OK with the current fix.
>
> Thanks,
> Shanliang
>
>
> About line 172, you are correct. I will just remove that line. Thanks!
>
> Mattias
>
> ----- Original Message -----
> From: shanliang.ji...@oracle.com To: daniel.fu...@oracle.com Cc:
> mattias.tobias...@oracle.com , serviceability-dev@openjdk.java.net Sent:
> Thursday, February 27, 2014 12:59:49 PM GMT +01:00 Amsterdam / Berlin / Bern
> / Rome / Stockholm / Vienna
> Subject: Re: RFR(XS) 8031065: LowMemoryTest2.sh fails: OutOfMemoryError:
> Metaspace
>
> Daniel Fuchs wrote:
>
> On 2/27/14 11:43 AM, Mattias Tobiasson wrote:
>
> Hi,
> Could you please review this test fix.
>
> The test verifies that MemoryPoolMXBean sends a notification when
> used memory has reached the threshold.
> The flag thresholdExceeded marks if we have reached the memory
> threshold. When the flag is set, the test slows down to give time for
> the notification to be received.
> The problem is that thresholdExceeded is overwritten every time in
> the loop. Instead it should be set if any pool has reached the
> threshold. This means that the test continues to allocate memory at
> full speed, and we may get an OutOfMemory before we get the
> notification. Hi Mattias,
>
> I wonder whether you should also stop calling loadNext() once
> thresholdExceeded is true? Yes I am thinking this too.
>
> Line 172 is unnecessary, after thresholdExceeded becomes true, Line 170
> will always be skipped.
>
> Shanliang
>
> best regards,
>
> -- daniel
>
> bug: https://bugs.openjdk.java.net/browse/JDK-8031065 webrev:
> http://cr.openjdk.java.net/~ykantser/8031065/webrev.00/ Mattias
>
# HG changeset patch
# User mtobiass
# Date 1393582400 -3600
# Node ID 6b98516e31343740f7d24bbcb939deef1a0fb2a2
# Parent 0731952efb104b783b75a5765a91a91601903a3c
8031065: java/lang/management/MemoryMXBean/LowMemoryTest2.sh fails: OutOfMemoryError: Metaspace
Summary: Load classes until getUsageThresholdCount() > 0 instead of isUsageThresholdExceeded().
Contributed-by: mattias.tobias...@oracle.com
diff --git a/test/java/lang/management/MemoryMXBean/LowMemoryTest2.java b/test/java/lang/management/MemoryMXBean/LowMemoryTest2.java
--- a/test/java/lang/management/MemoryMXBean/LowMemoryTest2.java
+++ b/test/java/lang/management/MemoryMXBean/LowMemoryTest2.java
@@ -67,7 +67,7 @@
static int count = 100000;
- Class loadNext() throws ClassNotFoundException {
+ Class loadNext() {
// public class TestNNNNNN extends java.lang.Object{
// public TestNNNNNN();
@@ -135,63 +135,49 @@
}
/*
- * Run method for thread that continuously loads classes.
- *
- * Note: Once the usage threshold has been exceeded the low memory
- * detector thread will attempt to deliver its notification - this can
- * potentially create a race condition with this thread contining to
- * fill up metaspace. To avoid the low memory detector getting an
- * OutOfMemory we throttle this thread once the threshold has been
- * exceeded.
+ * Load classes until MemoryPoolMXBean.getUsageThresholdCount() > 0.
+ * Then wait for the memory threshold notification to be received.
*/
public void run() {
- List pools = ManagementFactory.getMemoryPoolMXBeans();
+ List<MemoryPoolMXBean> pools = ManagementFactory.getMemoryPoolMXBeans();
boolean thresholdExceeded = false;
- for (;;) {
- try {
- // the classes are small so we load 10 at a time
- for (int i=0; i<10; i++) {
- loadNext();
- }
- } catch (ClassNotFoundException x) {
- return;
- }
- if (listenerInvoked) {
- return;
+ // Load classes until MemoryPoolMXBean.getUsageThresholdCount() > 0
+ while (!thresholdExceeded) {
+ // the classes are small so we load 10 at a time
+ for (int i=0; i<10; i++) {
+ loadNext();
}
- // if threshold has been exceeded we put in a delay to allow
- // the low memory detector do its job.
- if (thresholdExceeded) {
- try {
- Thread.currentThread().sleep(100);
- } catch (InterruptedException x) { }
- } else {
- // check if the threshold has been exceeded
- ListIterator i = pools.listIterator();
- while (i.hasNext()) {
- MemoryPoolMXBean p = (MemoryPoolMXBean) i.next();
- if (p.getType() == MemoryType.NON_HEAP &&
- p.isUsageThresholdSupported())
- {
- thresholdExceeded = p.isUsageThresholdExceeded();
- }
+ // check if the threshold has been exceeded
+ for (MemoryPoolMXBean p : pools) {
+ if (p.getType() == MemoryType.NON_HEAP &&
+ p.isUsageThresholdSupported() &&
+ p.getUsageThresholdCount() > 0)
+ {
+ thresholdExceeded = true;
+ break;
}
}
}
+
+ System.out.println("thresholdExceeded. Waiting for notification");
+ while (!listenerInvoked) {
+ try {
+ Thread.currentThread().sleep(10);
+ } catch (InterruptedException x) {}
+ }
}
}
public static void main(String args[]) {
- ListIterator iter = ManagementFactory.getMemoryPoolMXBeans().listIterator();
+ List<MemoryPoolMXBean> pools = ManagementFactory.getMemoryPoolMXBeans();
// Set threshold of 80% of all NON_HEAP memory pools
// In the Hotspot implementation this means we should get a notification
// if the CodeCache or metaspace fills up.
- while (iter.hasNext()) {
- MemoryPoolMXBean p = (MemoryPoolMXBean) iter.next();
+ for (MemoryPoolMXBean p : pools) {
if (p.getType() == MemoryType.NON_HEAP && p.isUsageThresholdSupported()) {
// set threshold
