Konrad Windszus created SLING-5847:
--------------------------------------
Summary: Deadlock in
JcrResourceBundleProvider.getResourceBundleInternal
Key: SLING-5847
URL: https://issues.apache.org/jira/browse/SLING-5847
Project: Sling
Issue Type: Bug
Components: Extensions
Affects Versions: i18n 2.4.4
Reporter: Konrad Windszus
Assignee: Konrad Windszus
Under particular timing situations the {{reloadBundle}} job and a parallel call
to {{JcrResourceBundleProvider.getResourceBundleInternal()}} might block each
other and also all new threads calling
{{JcrResourceBundleProvider.getResourceBundleInternal()}}.
The thread dump in that situation looks like follows
{code}
"0:0:0:0:0:0:0:1 [1468492407436] GET <some request url> HTTP/1.1" - Thread
t@69826
java.lang.Thread.State: BLOCKED
at
org.apache.sling.i18n.impl.JcrResourceBundleProvider.registerResourceBundle(JcrResourceBundleProvider.java:458)
- waiting to lock <19c60354> (a
org.apache.sling.i18n.impl.JcrResourceBundleProvider) owned by
"pool-8-thread-5" t@111
at
org.apache.sling.i18n.impl.JcrResourceBundleProvider.getResourceBundleInternal(JcrResourceBundleProvider.java:437)
at
org.apache.sling.i18n.impl.JcrResourceBundleProvider.createResourceBundle(JcrResourceBundleProvider.java:480)
at
org.apache.sling.i18n.impl.JcrResourceBundleProvider.getResourceBundleInternal(JcrResourceBundleProvider.java:435)
at
org.apache.sling.i18n.impl.JcrResourceBundleProvider.getResourceBundle(JcrResourceBundleProvider.java:185)
at
org.apache.sling.i18n.impl.I18NFilter$CombinedBundleProvider.getResourceBundle(I18NFilter.java:217)
at
org.apache.sling.i18n.impl.I18NFilter$BaseI18NSlingHttpServletRequest.getResourceBundle(I18NFilter.java:311)
at
org.apache.sling.api.wrappers.SlingHttpServletRequestWrapper.getResourceBundle(SlingHttpServletRequestWrapper.java:115)
at
org.apache.sling.api.wrappers.SlingHttpServletRequestWrapper.getResourceBundle(SlingHttpServletRequestWrapper.java:115)
at
org.apache.sling.api.wrappers.SlingHttpServletRequestWrapper.getResourceBundle(SlingHttpServletRequestWrapper.java:115)
at
org.apache.sling.api.wrappers.SlingHttpServletRequestWrapper.getResourceBundle(SlingHttpServletRequestWrapper.java:115)
at
org.apache.sling.api.wrappers.SlingHttpServletRequestWrapper.getResourceBundle(SlingHttpServletRequestWrapper.java:115)
at ...
"pool-8-thread-5" - Thread t@111
java.lang.Thread.State: WAITING
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <69b06467> (a
java.util.concurrent.Semaphore$NonfairSync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:997)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1304)
at java.util.concurrent.Semaphore.acquire(Semaphore.java:312)
at
org.apache.sling.i18n.impl.JcrResourceBundleProvider.getResourceBundleInternal(JcrResourceBundleProvider.java:429)
at
org.apache.sling.i18n.impl.JcrResourceBundleProvider.createResourceBundle(JcrResourceBundleProvider.java:480)
at
org.apache.sling.i18n.impl.JcrResourceBundleProvider.getResourceBundleInternal(JcrResourceBundleProvider.java:435)
at
org.apache.sling.i18n.impl.JcrResourceBundleProvider.getResourceBundle(JcrResourceBundleProvider.java:185)
at
org.apache.sling.i18n.impl.JcrResourceBundleProvider.reloadBundle(JcrResourceBundleProvider.java:357)
at
org.apache.sling.i18n.impl.JcrResourceBundleProvider.reloadBundle(JcrResourceBundleProvider.java:352)
at
org.apache.sling.i18n.impl.JcrResourceBundleProvider$2.run(JcrResourceBundleProvider.java:320)
- locked <19c60354> (a
org.apache.sling.i18n.impl.JcrResourceBundleProvider)
at
org.apache.sling.commons.scheduler.impl.QuartzJobExecutor.execute(QuartzJobExecutor.java:115)
at org.quartz.core.JobRunShell.run(JobRunShell.java:202)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
{code}
Here is what happens internally:
Thread 1 has acquired a semaphore for a specific key and now waits for the lock
hold by thread 2 in
{code}
private void registerResourceBundle(Key key, JcrResourceBundle resourceBundle)
{
Dictionary<Object, Object> serviceProps = new Hashtable<Object,
Object>();
if (key.baseName != null) {
serviceProps.put("baseName", key.baseName);
}
serviceProps.put("locale", key.locale.toString());
ServiceRegistration serviceReg =
bundleContext.registerService(ResourceBundle.class.getName(),
resourceBundle, serviceProps);
-> synchronized (this) {
bundleServiceRegistrations.put(key, serviceReg);
}
{code}
Thread 2 holds that lock in
{code}
private void scheduleReloadBundle(JcrResourceBundle bundle) {
String baseName = bundle.getBaseName();
Locale locale = bundle.getLocale();
final Key key = new Key(baseName, locale);
// defer this job
ScheduleOptions options = scheduler.AT(new
Date(System.currentTimeMillis() + invalidationDelay));
final String jobName = "JcrResourceBundleProvider: reload bundle with
key " + key.toString();
scheduledJobNames.add(jobName);
options.name(jobName);
scheduler.schedule(new Runnable() {
@Override
public void run() {
synchronized(JcrResourceBundleProvider.this) {
-> reloadBundle(key);
}
scheduledJobNames.remove(jobName);
}
}, options);
}
{code}
and now waits for the same semaphore that is being hold by thread 1.
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