[FELIX-5247] Reduce number of threads created by Resolver during a startup of OSGi-based applications

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: framework-5.4.0, resolver-1.8.0
• Fix Version/s: framework-5.6.1
• Component/s: Framework, Resolver
• Labels: performance
• Assignee: Guillaume Nodet
• Reporter: Dmitry Konstantinov
• Created: 03/May/16 14:47
• Updated: 21/Oct/16 20:56
• Resolved: 05/Oct/16 08:14

Description

Thread creation is a quite expensive operation, so it make sense to reuse threads in ResolverImpl if they are needed to split some task and do it in parallel.
For example: Apache Karaf startup with several features can install about 300 bundles. If each one will create Runtime.getRuntime().availableProcessors() threads - so, during a startup about 1000 threads will be created only by Resolver (in case of a server machine even much more). Thread creation takes let's say (depends on machine, JDK, OS, etc) about 10-20 ms, so we are spending about 1-2 seconds of startup time only to create some threads.

it make sense to create a thread pool once (with a configurable thread number) and reuse it for resolving of different bundles.

Threads creation, stack examples:

java.lang.Thread.<init>(ThreadGroup, Runnable, String, long) Thread.java
java.util.concurrent.Executors$DefaultThreadFactory.newThread(Runnable) Executors.java:613
java.util.concurrent.ThreadPoolExecutor$Worker.<init>(ThreadPoolExecutor, Runnable) ThreadPoolExecutor.java:612
java.util.concurrent.ThreadPoolExecutor.addWorker(Runnable, boolean) ThreadPoolExecutor.java:925
java.util.concurrent.ThreadPoolExecutor.execute(Runnable) ThreadPoolExecutor.java:1357
org.apache.felix.resolver.ResolverImpl$EnhancedExecutor.execute(Runnable) ResolverImpl.java:2436
org.apache.felix.resolver.ResolverImpl$1Computer.run() ResolverImpl.java:1150
org.apache.felix.resolver.ResolverImpl$EnhancedExecutor$1.run() ResolverImpl.java:2442
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor$Worker) ThreadPoolExecutor.java:1142
java.util.concurrent.ThreadPoolExecutor$Worker.run() ThreadPoolExecutor.java:617
java.lang.Thread.run() Thread.java:745

java.lang.Thread.<init>(ThreadGroup, Runnable, String, long) Thread.java
java.util.concurrent.Executors$DefaultThreadFactory.newThread(Runnable) Executors.java:613
java.util.concurrent.ThreadPoolExecutor$Worker.<init>(ThreadPoolExecutor, Runnable) ThreadPoolExecutor.java:612
java.util.concurrent.ThreadPoolExecutor.addWorker(Runnable, boolean) ThreadPoolExecutor.java:925
java.util.concurrent.ThreadPoolExecutor.execute(Runnable) ThreadPoolExecutor.java:1357
org.apache.felix.resolver.ResolverImpl$EnhancedExecutor.execute(Runnable) ResolverImpl.java:2436
org.apache.felix.resolver.ResolverImpl.calculatePackageSpaces(Executor, ResolverImpl$ResolveSession, Candidates, Collection) ResolverImpl.java:1158
org.apache.felix.resolver.ResolverImpl.checkConsistency(Executor, ResolverImpl$ResolveSession, List, List, Candidates, Map, Map, boolean) ResolverImpl.java:471
org.apache.felix.resolver.ResolverImpl.resolve(ResolveContext, Executor) ResolverImpl.java:347
org.apache.felix.resolver.ResolverImpl.resolve(ResolveContext) ResolverImpl.java:158
org.apache.felix.framework.StatefulResolver.resolve(Set, Set) StatefulResolver.java:431
org.apache.felix.framework.Felix.resolveBundleRevision(BundleRevision) Felix.java:4118
org.apache.felix.framework.Felix.startBundle(BundleImpl, int) Felix.java:2124
org.apache.felix.framework.BundleImpl.start(int) BundleImpl.java:998
org.apache.felix.framework.BundleImpl.start() BundleImpl.java:984
org.apache.karaf.features.internal.FeaturesServiceImpl.startBundle(InstallationState, Bundle) FeaturesServiceImpl.java:520
org.apache.karaf.features.internal.FeaturesServiceImpl.installFeatures(Set, EnumSet) FeaturesServiceImpl.java:478
org.apache.karaf.features.internal.FeaturesServiceImpl.installFeature(Feature, EnumSet) FeaturesServiceImpl.java:419
org.apache.karaf.features.internal.FeaturesServiceImpl.installFeature(String, String, EnumSet) FeaturesServiceImpl.java:394
org.apache.karaf.features.internal.FeaturesServiceImpl.installFeature(String, EnumSet) FeaturesServiceImpl.java:364

Issue Links

• relates to: KARAF-4748 Make Felix Resolver Threads configurable