Liferay Digital Enterprise Configuration and Tuning Guidelines

When tuning Liferay DXP installation, there are several factors to take into consideration; some are specific to Liferay DXP, while others are concepts that apply to all Java and Java enterprise applications. The following guidelines are meant to serve as an initial baseline from which to tune your specific deployment.

Application Server Tuning

Although the actual setting names may differ, these concepts are applicable across most application servers. For brevity, we will use Tomcat as an example. For other application servers, consult the application server provider’s documentation for additional specific settings.

Database Connection Pool

The database connection pool is usually sized at roughly 30-40% of the thread pool size. The connection pool provides a connection whenever Liferay DXP needs to retrieve data from the database (e.g. user login, etc.). If this size is too small, requests queue in the server waiting for database connections. Too large a setting, however, means wasting resources with idle database connections.

As with thread pools, monitor these settings and adjust them based on your performance tests.

In Tomcat, the connection pools are configured in the Resource elements in $CATALINA_HOME/conf/ Catalina/localhost/ROOT.xml. Liferay Engineering uses the following configuration during testing:

<Resource auth="Container"         
    description="Digital Enterprise DB Connection"   
    maxPoolSize="75"   minPoolSize="10"           

In this configuration, we start with 10 threads and increment by 5 as needed to a maximum of 75 connections in the pool.

You may choose from a variety of database connection pool providers, including DBCP, C3P0, HikariCP, and Tomcat. You may also choose to configure the Liferay JDBC settings in your

Deactivate Development Settings in the JSP Engine

Many application servers have their JSP Engines configured for development mode by default. Liferay recommends deactivating these settings prior to entering production:

Development mode: This makes the JSP container poll the file system for changes to JSP files. Since you won’t be making changes on the fly like this in production, you should turn this off.

Mapped File: Generates static content with one print statement versus one statement per line of JSP text.

To do this in Tomcat, you modify the $CATALINA_HOME/conf/web.xml file. Update the JSP servlet to look like the following configuration:


Thread Pool

Each incoming request to the application server consumes a worker thread for the duration of the request. When no threads are available to process requests, the request is queued to wait for the next available worker thread. In a finely tuned system, the number of threads in the thread pool should be balanced with the total number of concurrent requests. There should not be a significant amount of threads left idle to service requests.

Liferay Engineering recommends an initial setting of 50 threads and then monitoring it within your application server’s monitoring consoles. You may wish to use a higher number (e.g., 250) if your average page times are in the 2-3 seconds range. Too few threads in the thread pool may lead to excessive request queuing while too many threads may lead to excessive context switching.

In Tomcat, the thread pools are configured in the Connector element in $CATALINA_HOME/conf/server.xml. Further information can be found in the Apache Tomcat documentation. Liferay Engineering used the following configuration during testing:

<Connector maxThreads="75" minSpareThreads="50" 
    maxConnections="16384" port="8080"     
    connectionTimeout="600000" redirectPort="8443" 
    URIEncoding="UTF-8"  socketBuffer="-1"     
    maxKeepAliveRequests="-1" address=""/>

Additional tuning parameters around Connectors are available, including the connector types, the connection timeouts, and TCP queue. Consult the appropriate Tomcat documentation for further details.

Java Virtual Machine Tuning

Tuning the JVM primarily focuses on tuning the garbage collector and the Java memory heap. These parameters are used to optimize the throughput of your application. We used Oracle’s 1.8 JVM for the reference architecture. You may also choose other supported JVM versions and implementations. Please consult the Liferay Digital Enterprise Compatibility Matrix for additional compatible JVMs.

Garbage Collector

Choosing the appropriate garbage collector (GC) helps improve the responsiveness of your Liferay DXP deployment. Liferay recommends using the concurrent low pause collectors:

-XX:+UseParNewGC -XX:ParallelGCThreads=16 -XX:+UseConcMarkSweepGC
-XX:+CMSParallelRemarkEnabled -XX:+CMSCompactWhenClearAllSoftRefs
-XX:CMSInitiatingOccupancyFraction=85 -XX:+CMSScavengeBeforeRemark

You may choose from other available GC algorithms including parallel throughput collectors and G1 collectors. Liferay recommends first starting your tuning using parallel collectors in the new generation and concurrent mark sweep (CMS) in the old generation.

Note: the value 16 in ParallelGCThreads=16 varies based on the type of CPUs available. We recommend setting the value according to CPU specification. On Linux machines, you may find the number of available CPUs by running cat /proc/cpuinfo.

Note: There are additional “new” algorithms like G1, but Liferay Engineering’s tests for G1 have indicated that it does not improve performance. Your application performance may vary and you should add it to your testing and tuning plans.

Code Cache

Java uses a just-in-time (JIT) compiler that generates native code to improve performance. The default size is 48M. This may not be sufficient for larger applications. Too small a code cache reduces performance as the JIT isn’t able to optimize high frequency methods. For Digital Enterprise, we recommend starting with 64M for the initial code cache size.

-XX:InitialCodeCacheSize=32m -XX:ReservedCodeCacheSize=96m

You can examine the efficacy of the parameter changes by adding the following parameters:

-XX:+PrintCodeCache -XX:+PrintCodeCacheOnCompilation

Java Heap

When most people think about tuning the Java memory heap, they think of setting the maximum and minimum memory of the heap. Unfortunately, most deployments require far more sophisticated heap tuning to obtain optimal performance, including tuning the young generation size, tenuring durations, survivor spaces and many other JVM internals.

For most systems, Liferay recommends starting with at least the following memory settings:

-server -XX:NewSize=700m -XX:MaxNewSize=700m -Xms2048m -Xmx2048m -XX:MetaspaceSize=300m
-XX:MaxMetaspaceSize=300m -XX:SurvivorRatio=6 -XX:TargetSurvivorRatio=9 -XX:MaxTenuringThreshold=15

On systems that require large heap sizes (e.g., above 4GB), it may be beneficial to use large page sizes. You may activate large page sizes using the following JVM options:

-XX:+UseLargePages -XX:LargePageSizeInBytes=256m

You may choose to specify different page sizes based on your application profile.

Note: To use large pages in the JVM, you must configure your underlying operation system to activate them. In Linux, run cat /proc/meminfo and look at “huge page” items.

JVM Advanced Options

The following advanced JVM options were also applied in the Liferay benchmark environment:

-XX:+UseLargePages -XX:LargePageSizeInBytes=256m 
-XX:+UseCompressedOops -XX:+DisableExplicitGC -XX:-UseBiasedLocking 
-XX:+BindGCTaskThreadsToCPUs -XX:UseFastAccessorMethods

Please consult your JVM documentation for additional details on advanced JVM options.

Combining the above recommendations together, we have this configuration:

-server -XX:NewSize=1024m -XX:MaxNewSize=1024m -Xms4096m
-Xmx4096m -XX:MetaspaceSize=300m -XX:MaxMetaspaceSize=300m
-XX:SurvivorRatio=12 -XX:TargetSurvivorRatio=90
-XX:MaxTenuringThreshold=15 -XX:+UseLargePages 
-XX:LargePageSizeInBytes=256m -XX:+UseParNewGC 
-XX:ParallelGCThreads=16 -XX:+UseConcMarkSweepGC 
-XX:+CMSParallelRemarkEnabled -XX:+CMSCompactWhenClearAllSoftRefs
-XX:CMSInitiatingOccupancyFraction=85 -XX:+CMSScavengeBeforeRemark 
-XX:+UseLargePages -XX:LargePageSizeInBytes=256m
-XX:+UseCompressedOops -XX:+DisableExplicitGC -XX:-UseBiasedLocking
-XX:+BindGCTaskThreadsToCPUs -XX:+UseFastAccessorMethods
-XX:InitialCodeCacheSize=32m -XX:ReservedCodeCacheSize=96m

Liferay recommends monitoring the garbage collector statistics to ensure your environment has sufficient allocations for metaspace and also for the survivor spaces. Simply using the guideline numbers above may result in dangerous runtime scenarios like out of memory failures. Improperly tuned survivor spaces also lead to wasted heap space.

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