Start/notes.ini Parameters/JavaMaxHeapSize

JavaMaxHeapSize

Parameter: JavaMaxHeapSize
Short description: Sets the maximum JVM heap size for all Domino server processes outside the HTTP task (Agent Manager, periodic Java agents, runjava). Default: 256 MB.
JavaMaxHeapSize sets the maximum heap size of the Java Virtual Machine for all Domino server processes other than the HTTP task — for example Agent Manager (amgr), periodic Java agents, and runjava calls.

Profile

Parameter
JavaMaxHeapSize
Component
Server (amgr, runjava, Java agents)
Category
Performance / Memory (JVM)
Available since
9.0.x (per KB0029777)
Default
256 MB on HCL Domino Server
Values
Bytes or with suffix M/MB
Scope
All JVM users except the HTTP task
Activation
Restart of the relevant tasks (e.g. restart task amgr)

Description

Domino distinguishes between two controls for JVM heap sizes:
  • JavaMaxHeapSize sets the heap for all Domino processes that start their own JVM — e.g. Agent Manager (amgr), periodic Java agents, or runjava calls.
  • HTTPJVMMaxHeapSize sets the heap only for the HTTP task (nhttp).
According to HCL Customer Support (KB0029777), the default value of JavaMaxHeapSize is 256 MB, that of HTTPJVMMaxHeapSize is 1 GB.
The JVM typically starts with around 16 MB of heap and grows as needed up to the maximum defined with JavaMaxHeapSize. When the maximum is reached, java.lang.OutOfMemoryError occurs.

Examples

JavaMaxHeapSize=64MB
JavaMaxHeapSize=512M
JavaMaxHeapSize=67108864
The three examples are not equivalent: 64 MB = 67,108,864 bytes; 512 M = 512 MB.

Practical notes

  • OutOfMemory in Java agents – if a periodic Java agent reports java.lang.OutOfMemoryError, JavaMaxHeapSize is too low (or the agent has a memory leak).
  • Separation from HTTP – changes to JavaMaxHeapSize do not affect the HTTP task. For XPages and Java DSAPI, HTTPJVMMaxHeapSize is responsible.
  • Activation – the value is read on the next start of the respective JVM. For Agent Manager: restart task amgr on the server console.
  • Older defaults – in much older releases there were different defaults (e.g. 64 MB in Domino 7/8). On HCL Domino Server (9.x and newer), 256 MB is the standard.

Sources (HCL Product Documentation)