A simple diagnostic utility I use to detect these problems:
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import org.apache.ignite.Ignite;
import org.apache.ignite.internal.GridComponent;
import org.apache.ignite.internal.IgniteKernal;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
public class IgniteWeakRefTracker {
private static final Logger LOGGER =
LogManager.getLogger(IgniteWeakRefTracker.class);
private final String clazz;
private final String testName;
private final String name;
private final WeakReference<Ignite> innerRef;
private final List<WeakReference<GridComponent>>
componentRefs = new ArrayList<>(128);
private static final LinkedList<IgniteWeakRefTracker> refs =
new LinkedList<>();
private IgniteWeakRefTracker(String testName, Ignite ignite) {
this.clazz = ignite.getClass().getCanonicalName();
this.innerRef = new WeakReference<>(ignite);
this.name <http://this.name> = ignite.name <http://ignite.name>();
this.testName = testName;
if (ignite instanceof IgniteKernal) {
IgniteKernal ik = (IgniteKernal) ignite;
List<GridComponent> components =
ik.context().components();
for (GridComponent c : components) {
componentRefs.add(new WeakReference<>(c));
}
}
}
public static void register(String testName, Ignite ignite) {
refs.add(new IgniteWeakRefTracker(testName, ignite));
}
public static void trimCollectedRefs() {
List<IgniteWeakRefTracker> toRemove = new ArrayList<>();
for (IgniteWeakRefTracker ref : refs) {
if (ref.isIgniteCollected()) {
LOGGER.info("Collected ignite: ignite {} from
test {}", ref.getIgniteName(), ref.getTestName());
toRemove.add(ref);
if (ref.igniteComponentsNonCollectedCount() != 0) {
throw new IllegalStateException("Non
collected components for collected ignite.");
}
} else {
LOGGER.warn("Leaked ignite: ignite {} from test
{}", ref.getIgniteName(), ref.getTestName());
}
}
refs.removeAll(toRemove);
LOGGER.info("Leaked ignites count: {}", refs.size());
}
public static int getLeakedSize() {
return refs.size();
}
public boolean isIgniteCollected() {
return innerRef.get() == null;
}
public int igniteComponentsNonCollectedCount() {
int res = 0;
for (WeakReference<GridComponent> cr : componentRefs) {
GridComponent gridComponent = cr.get();
if (gridComponent != null) {
LOGGER.warn("Uncollected component: {}",
gridComponent.getClass().getSimpleName());
res++;
}
}
return res;
}
public String getClazz() {
return clazz;
}
public String getTestName() {
return testName;
}
public String getIgniteName() {
return name;
}
}
On Fri, Mar 20, 2020 at 11:51 PM Andrey Davydov
<[email protected] <mailto:[email protected]>> wrote:
I found one more way for leak and understand reason:
this - value: org.apache.ignite.internal.IgniteKernal #1
<- grid - class:
org.apache.ignite.internal.GridKernalContextImpl, value:
org.apache.ignite.internal.IgniteKernal #1
<- ctx - class:
org.apache.ignite.internal.processors.timeout.GridTimeoutProcessor,
value: org.apache.ignite.internal.GridKernalContextImpl #3
<- this$0 - class:
org.apache.ignite.internal.processors.timeout.GridTimeoutProcessor$CancelableTask,
value:
org.apache.ignite.internal.processors.timeout.GridTimeoutProcessor
#1
<- stmtCleanupTask - class:
org.apache.ignite.internal.processors.query.h2.ConnectionManager,
value:
org.apache.ignite.internal.processors.timeout.GridTimeoutProcessor$CancelableTask
#11
<- arg$1 - class:
org.apache.ignite.internal.processors.query.h2.ConnectionManager$$Lambda$174,
value:
org.apache.ignite.internal.processors.query.h2.ConnectionManager
#1
<- recycler - class:
org.apache.ignite.internal.processors.query.h2.ThreadLocalObjectPool,
value:
org.apache.ignite.internal.processors.query.h2.ConnectionManager$$Lambda$174
#1
<- this$0 - class:
org.apache.ignite.internal.processors.query.h2.ThreadLocalObjectPool$Reusable,
value:
org.apache.ignite.internal.processors.query.h2.ThreadLocalObjectPool
#1
<- value - class:
java.lang.ThreadLocal$ThreadLocalMap$Entry, value:
org.apache.ignite.internal.processors.query.h2.ThreadLocalObjectPool$Reusable
#1
<- [411] - class:
java.lang.ThreadLocal$ThreadLocalMap$Entry[], value:
java.lang.ThreadLocal$ThreadLocalMap$Entry #35
<- table - class:
java.lang.ThreadLocal$ThreadLocalMap, value:
java.lang.ThreadLocal$ThreadLocalMap$Entry[] #25
<- threadLocals (thread object) - class:
java.lang.Thread, value: java.lang.ThreadLocal$ThreadLocalMap #2
Reason:
org.apache.ignite.internal.processors.query.h2.ConnectionManager
has some ThreadLocal fields, including connPool,
threadConns, threadConn, detachedConns etc.
ConnectionManager store Lambdas it this thread local
storages, so link to ConnectionManager leaks to thread local
context.
And seems that method not valid enoght
private void closeConnections() {
threadConns.values().forEach(set ->
set.keySet().forEach(U::closeQuiet));
detachedConns.keySet().forEach(U::closeQuiet);
threadConns.clear();
detachedConns.clear();
}
So when Ignition.start() and Ignition.stop() was from
different thread, caches not cleared properly and starter
thread save link to ConnectionManager via ThreadLocal
context. And we get one Ignite instance leak every time.
Im sure you run "tens of thousands nodes during every suite
run." But majority of runs may be without Indexing, and start
and stop node in same thread.
To reproduce leak, start ignite with indexing, save lint to
weak reference, and stop it asynchroniouly in other thread,
null local link, check weak ref and see heap dump.
Andrey.
*От: *Andrey Davydov<mailto:[email protected]>
*Отправлено: *18 марта 2020 г. в 18:37
*Кому: *[email protected]<mailto:[email protected]>
*Тема: *Ignite memory leaks in 2.8.0
Hello,
There are at least two way link to IgniteKernal leaks to GC
root and makes it unavailable for GC.
1. The first one:
this - value: org.apache.ignite.internal.IgniteKernal #1
<- grid - class:
org.apache.ignite.internal.GridKernalContextImpl, value:
org.apache.ignite.internal.IgniteKernal #1
<- ctx - class:
org.apache.ignite.internal.processors.query.h2.IgniteH2Indexing,
value: org.apache.ignite.internal.GridKernalContextImpl #2
<- this$0 - class:
org.apache.ignite.internal.processors.query.h2.IgniteH2Indexing$10,
value:
org.apache.ignite.internal.processors.query.h2.IgniteH2Indexing
#2
<- serializer - class: org.h2.util.JdbcUtils, value:
org.apache.ignite.internal.processors.query.h2.IgniteH2Indexing$10
#1
<- [5395] - class: java.lang.Object[], value:
org.h2.util.JdbcUtils class JdbcUtils
<- elementData - class: java.util.Vector, value:
java.lang.Object[] #37309
<- classes - class: sun.misc.Launcher$AppClassLoader,
value: java.util.Vector #31
<- contextClassLoader (thread object) - class:
java.lang.Thread, value: sun.misc.Launcher$AppClassLoader #1
org.h2.util.JdbcUtils has static field JavaObjectSerializer
serializer, which see IgniteKernal via IgniteH2Indexing. It
make closed and stopped IgniteKernal non collectable by GC.
If some Ignites run in same JVM, JdbcUtils will always use
only one, and it can cause some races.
2. The second way:
this - value: org.apache.ignite.internal.IgniteKernal #2
<- grid - class:
org.apache.ignite.internal.GridKernalContextImpl, value:
org.apache.ignite.internal.IgniteKernal #2
<- ctx - class:
org.apache.ignite.internal.processors.cache.GridCacheContext,
value: org.apache.ignite.internal.GridKernalContextImpl #1
<- cctx - class:
org.apache.ignite.internal.processors.cache.distributed.dht.GridDhtCacheEntry,
value:
org.apache.ignite.internal.processors.cache.GridCacheContext #24
<- parent - class:
org.apache.ignite.internal.processors.cache.GridCacheMvccCandidate,
value:
org.apache.ignite.internal.processors.cache.distributed.dht.GridDhtCacheEntry
#4
<- [0] - class: java.lang.Object[], value:
org.apache.ignite.internal.processors.cache.GridCacheMvccCandidate
#1
<- elements - class: java.util.ArrayDeque, value:
java.lang.Object[] #43259
<- value - class:
java.lang.ThreadLocal$ThreadLocalMap$Entry, value:
java.util.ArrayDeque #816
<- [119] - class:
java.lang.ThreadLocal$ThreadLocalMap$Entry[], value:
java.lang.ThreadLocal$ThreadLocalMap$Entry #51
<- table - class: java.lang.ThreadLocal$ThreadLocalMap,
value: java.lang.ThreadLocal$ThreadLocalMap$Entry[] #21
<- threadLocals (thread object) - class:
java.lang.Thread, value: java.lang.ThreadLocal$ThreadLocalMap #2
Link to IgniteKernal leaks to ThreadLocal variable, so when
we start/stop many instances of Ignite in same jvm during
testing, we got many stopped “zomby” ignites on ThreadLocal
context of main test thread and it cause OutOfMemory after
some dozens of tests.
Andrey.
