Java VM Memory Settings

The Java VM memory settings for StreamBase Studio and StreamBase Server are defined independently in different ways, as described in later sections of this page. The default settings are slightly different between Studio and Server. The settings in this table apply to 64-bit Server running on Windows and UNIX systems:

The -XX:MaxPermSize setting is no longer used by Java 8, and this setting is ignored when using the JDK 8 bundled with StreamBase release 7.6.0 and later.

In addition, the default JVM settings include -XX:+UseCompressdOops.

In most cases, you only need to be concerned with the JVM settings for StreamBase Server, discussed in the following sections. For editing very large applications in Studio, you might need to separately increase Studio's memory footprint, as described in JVM Memory for StreamBase Studio.

Remember that StreamBase Studio running in one Java VM launches StreamBase Server in a separate JVM process with its own memory constraints. Increasing only Studio's memory settings does not help the server load a large application; in fact, it could hamper it.

In a sense, Studio and Server must compete for memory resources on memory-constrained systems. For this reason, only increase Studio's JVM memory settings by the minimum amount that supports acceptable response times for typechecking and editing large applications. For example, on an 8 GB 64-bit system used for editing a large StreamBase application, you might allocate up to 2 GB for Studio, and leave the rest for server launches.

Any memory allocated by native code in the Server startup process is allocated before the JVM starts. Thus, memory allocated by native code Server components is outside the JVM heap and competes for overall memory resources with both Studio and Server.

Native code memory allocations include any memory allocated by the native code portion of the sbd launcher, as well as memory allocated by native code operators and adapters, and by native code DLLs or .so files called by operators or adapters. For example, the native code portion of the sbd launcher allocates some memory for use as a cache for disk-based Query Tables. If you increase the disk-querytable-cache parameter of the <server> element of the server configuration file to a large value, the memory allocated is unavailable for use in the server's JVM heap.

It bears repeating that Studio is designed for authoring, testing, and debugging of applications, but is not designed to host high performance runs of StreamBase Server or for benchmarking of server runs, as discussed in Studio Performance Note.

If you start StreamBase Server without a configuration file, it starts with the internal default settings shown in the table above. You can adjust JVM memory settings for StreamBase Server in the server configuration file. The overall XML syntax for configuration files is described in StreamBase Server Configuration File XML Reference, in the <java-vm> section.

When you generate a default StreamBase Server configuration file in Studio and you opt to include the default contents, or when you generate a default configuration file with sbd –s, the new file contains the following suggested settings for the <java-vm> element:

<java-vm>
  <param name="jvm-args" value="
    -XX:+UseG1GC
    -XX:MaxGCPauseMillis=500 "/>
</java-vm>

The default GC settings are described in Garbage Collection Policy Settings.

Increase the memory available to the next launch of the server by adding entries for the -X settings from the table above. For a medium sized application, use settings like the following:

    -Xms1g -Xmx2g

For a large application, use settings like these:

    -Xms2g -Xmx4g

In general, StreamBase users do not need to adjust the JVM memory settings for running Studio. When Studio runs or debugs an application on the same machine, it launches StreamBase Server as a separate Java process with its own memory settings.

When Studio launches an application, it honors the <java-vm> settings in a server configuration file named sbd.sbconf that is placed at the root of the application's project folder. (Studio does not use configuration files with other names, or those placed in other folders.) Thus, Studio running with its default memory settings can launch a server process with larger memory settings defined in sbd.sbconf, as long as there is enough system memory (including virtual memory) to support the launch.

An exception exists for those editing very large StreamBase applications with hundreds of components and many sub-modules. In this case, typechecking time and system response time can improve with larger Studio memory settings.

Adjust Studio's JVM memory settings by setting the STREAMBASE_STUDIO_VMARGS environment variable for the environment in which Studio starts, as described in STREAMBASE_STUDIO_VMARGS. For example, the following setting provides an increase the default values:

STREAMBASE_STUDIO_VMARGS=-Xms1024M -Xmx2048M

Verify that your machine has enough system memory to support simultaneous editing and launching of large applications. 64-bit Windows and Linux systems should have 4 GB to take advantage of large JVM settings, with more recommended.

Follow these rules when changing Studio JVM memory settings:

You can configure StreamBase Studio to display its own Java heap memory usage. Run Window → Preferences, select the top-level General page, and select the Show heap status check box. Thereafter, Studio shows current and maximum reserved heap memory usage on the far right of the status bar, in the lower right corner of the Studio window.

To diagnose and troubleshoot memory usage with StreamBase Server, consider adding these additional settings in the jvm-args parameter. These settings cause additional information to be reported to the server console (or to the Console view in Studio) unless specifically overridden.

You can also use the following tools provided by StreamBase or included as part of its Java installation to inspect memory usage. The tools are listed in order of application-level to Java object-level inspection.