Heap Space issue in flow

[ARAVINDA11]

@Ankur Bawiskar  @Community Alums  @Sohail Khilji  @Maik Skoddow  or anyone please help

How can I solve the Heap size issue 

what is the maximum memory size is allowed in MID SERVER

[AJ-TechTrek]

Hi @ARAVINDA11 ,

Lets Understanding MID Server Heap Size Issue-

* The MID Server runs as a Java application (Java Virtual Machine – JVM).
* By default, the JVM heap size is limited (often 256 MB – 512 MB, depending on the OOTB config).
* Heavy Discovery jobs, multiple probes/sensors, or integrations (like Orchestration / Cloud Discovery) can cause OutOfMemoryError: Java heap space.

How to Solve Heap Size Issues as per my understanding -

1. Increase MID Server Heap Size
You can tune the JVM memory allocation for the MID Server:

1. On the MID Server host, go to:
<MID Server Install Dir>/agent/conf/wrapper-override.conf
2. 
(If wrapper-override.conf does not exist, copy from wrapper.conf).
3. Add or update these lines:
wrapper.java.maxmemory=2048
4. wrapper.java.initmemory=512
* initmemory = Initial heap size (MB).
* maxmemory = Maximum heap size (MB).
6. Example:
* Small workloads: 1024 MB
* Medium workloads: 2048 MB
* Large-scale Cloud Discovery: 4096 MB
7. Restart the MID Server service.

2. Tune Thread Settings
* Too many concurrent probes can overwhelm memory.
* Adjust in MID Server Configuration (instance > MID Server record > Capabilities/Properties):
* mid.max_threads
* mid.probe.batch.size
* Lowering concurrency reduces heap spikes.

3. Distribute Load Across Multiple MID Servers
* Don’t overload one MID Server.
* Use clusters and assign discovery schedules to spread jobs.
* For large Discovery jobs (Cloud, VMware, etc.), use dedicated MIDs.

4. Monitor Heap Usage
* Check agent.log and wrapper.log under:
<MID Server Install Dir>/agent/logs
* Look for OutOfMemoryError.
* Use OS monitoring tools (Windows Performance Monitor, Linux top/free).

Maximum Memory Allowed
* Technically, the max depends on:
* OS architecture (32-bit vs 64-bit).
* Installed Java version.
* 64-bit Java + OS: up to 4–8 GB heap is safe (though rarely needed above 4 GB).
* ServiceNow recommends max 4096 MB (4 GB) unless you have extreme workloads.

Recommended Best Practice
* Start with 2048 MB heap.
* If you still hit OOM errors, scale horizontally (add more MID Servers) instead of infinitely increasing heap.
* Use dedicated MIDs for heavy probes (Cloud, DB, Orchestration).

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Thank You
AJ - TechTrek with AJ - ITOM Trainer
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