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When the Maximum Heap Space size is too low for that is actually needed by the Java process, the following exception will be thrown: java.lang.OutOfMemoryError: Java heap space
Java Perm Space (java 7)
The Perm Space is the space used by Java to store loaded classes and other static objects. The setting related to the Java Perm Space is only the following.
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The above mentioned settings are settings that can be applied when launching a Java process command-line or form a .bat/.sh script. Certain application might provide other ways to specify the same settings, for example the Service component that is part of the Servoy distribution. For more information on how to configure these settings withing Servoy, read the next paragraph.
Java metaspace (java 8 and higher, replacement of the java 7 perm space above)
Java 8 changed the way it stored classes and is using now native memory for that instead of a special java heap
these settings can be adjusted by using the following vm arguments:
-XX:MetaspaceSize=200M -XX:MaxMetaspaceSize=200M -XX:MinMetaspaceFreeRatio=0 -XX:MaxMetaspaceFreeRatio=100
this sets it to use 200MB for that if you get a java.lang.OutOfMemoryError: metaspace because a lot of plugins are used then you need to update that value to something higher like 300/400.
Server Memory Management
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- Java Heap Space: 1280Mb
- Java Perm Space: 128Mb (java7)
- Java meta space: 200Mb (java8+)
Depending on how the Servoy Application Server is launched, the location where these values can be managed differs:
- Started using the Service component >
{serverInstall}\application_server\service\wrapper.conf - Manually started stand-alone >
{serverInstall}\application_server\servoy_server.bat/.sh - Manually started in Servoy Cluster >
{serverInstall}\application_server\terracotta/start_servoy_clustered.bat/.sh
Determining
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the Required Java Heap Space Value
The components that contribute to the Java Heap Space requirements for a Servoy Application Server consists of the following parts:
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- Smart Client using the Servoy HTTP Tunnel: assume 900kb for each Smart Client
- Smart Client using another connection mode than the HTTP tunnel: assume 600kb for each Smart Client
- Web Client, Headless Client (incl. the RESTfull plugin connection poolsize) & Batch processors: the required memory for each client depends on the size and design of the solution, but should be in the order of magnitude of a couple of Mb per Client. For more guidelines, see below.
Smart Client Memory usage Usage vs. other Other Servoy Client
The Smart Client runs on the client machine, not on the Servoy Application Server like the other Servoy Clients, like the Web Client, Headless Client or Batch Processor. The Smart Client is only registered with the Application Server and thus consumes far less memory on the Application Server compared to the other Servoy Clients. See Smart Client Memory management for more information on configuring the Memory settings for Smart Clients specifically.
Web Client, Headless Client & Batch processors memory usageProcessors Memory Usage
The memory usage of Web Clients, Headless Clients and Batch Processors depends highly on the design of the solution. While Servoy optimizes many things to keep the memory footprint as low as possible, it is logical that a simple solution showing just one form at the time has a different memory footprint than a solution that has a very complex UI, showing 20 Forms and/or different sets of data at the same time.
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- Small solution (1 - 50 forms), simple user interface: 2Mb
- Medium size solution (51 - 500 forms), average complex user interface: 10Mb
- Large solution (> 500 forms), complex user interface: 20Mb
Configuring
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the Java Heap Space Value
The setting that requires tuning based on the determined required memory for the Servoy Application Server is the Maximum Heap Space setting (Xmx). By default the Maximum Heap Space is set to 1028MB within Servoy. This setting should be changed when:
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When using the Service component to automatically launch the Servoy Application Server when the machine on which it is installed is booted, the memory settings for the Application Server can be configured inside {serverInstall}\application_server\service\wrapper.conf by altering the wrapper.java.maxmemory setting:
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wrapper.java.additional.5=-XX:MetaspaceSize=200M wrapper.java.additional.6=-XX:MaxMetaspaceSize=200M wrapper.java.additional.7=-XX:MinMetaspaceFreeRatio=0 wrapper.java.additional.8=-XX:MaxMetaspaceFreeRatio=100 wrapper.java.additional.49=-XX:MaxPermSize=128m wrapper.java.additional.10=-XX:+UseG1GC # make sure that the hardcoded System.gc() or Runtime.gc() are ignored (rmi does this) wrapper.java.additional.11=-XX:+DisableExplicitGC # Initial Java Heap Size (in MB), when G1GC is used just set the init memory to the max memory wrapper.java.initmemory=321280 # Maximum Java Heap Size (in MB) wrapper.java.maxmemory=1280 |
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| Code Block |
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java ... -Djava.awt.headless=true -Xmx1280m -Xms64m -XX:MetaspaceSize=200M -XX:MaxMetaspaceSize=200M -XX:MaxPermSize=128mMinMetaspaceFreeRatio=0 -XX:MaxMetaspaceFreeRatio=100 ..... |
| Note | ||
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When specifying the -Xmx and -Xms values, the following needs to be taken into account:
In a default Servoy Application Server installation, the Maximum Heap Space value (-Xmx) is set to 1280m. For servers that have limited memory, this value could be too high, resulting in the following error when trying to start the server:
Either lower the -Xmx value or make sure that more memory is available for the Java process on the server, by closing other applications or adding more physical memory to the server. |
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An 32 bit JVM will allow a maximum memory assignment of 2Gb in total. In order to assign more than 2Gb of memory, a 64 bit JVM on a 64 bit OS is required.
Determining
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the Required Java Metaspace or Perm Space Value
By default the Java Heap Space size is set to 128Mb/200Mb, which is a sufficient value for most deployments. A scenario in which this value needs increasing is when the Servoy Application Server is loaded up with a lot of additional plugins, beans, LAF's and drivers.
Configuring
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the Java Perm/Metaspace Space Value
For all three scenario's that the Servoy Application Server can be started (as a service, manual stand-alone or manual clustered), the value for the Java Perm Space is controlled by the 'XX:MaxPermSize' setting in the above mentioned configuration location .
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for java 7 or for java 8:
-XX:MetaspaceSize=200M -XX:MaxMetaspaceSize=200M -XX:MinMetaspaceFreeRatio=0 -XX:MaxMetaspaceFreeRatio=100
Monitoring the Memory Usage
The actual memory usage of a Servoy Application Server can be observed on the Servoy Admin page. The 'Servoy Server Status' overview on the 'Servoy Server Home' page displays the allocated, used and maximum values for the Heap memory and all other spaces combined (non-Heap memory).
Or through Monitoring Servoy with JMX
Running big servers with big heaps for many Web/NGClients
For large heaps (more then 4G) that needs to handle quite a lot of Web or NGClients the vm needs some tuning to be able to handle this nicely.
Use the latest Java 8 and use the G1 Garbagabe collector for this and make sure that the initial heap and the maximum heap ist just set to the same value:
-server -Xms4G -Xmx4G -XX:+UseG1GC -XX:MetaspaceSize=200M -XX:MaxMetaspaceSize=200M -XX:MinMetaspaceFreeRatio=0 -XX:MaxMetaspaceFreeRatio=100 -XX:+DisableExplicitGC
Where the 4G for the initial (Xms) and the max (Xmx) should be set to the maximum heap you want or can assign to the java vm.
Smart Client Memory Management
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