Can I set the CPU Core for the context thread in JavaRTO API?

Blogs & Tutorials
1

Is there the ability to define the core to which a given thread will be pinned to?

2

Yes, you can set the thread affinity of the automatically created context thread.
The relevant context properties for the underlying C API can be found here.

From within JavaRTO, you can provide the required “CONTEXT_THREAD_AFFINITY” property on context creation like so:

String[] contextProperties = new String[4]; 
int index = 0;
contextProperties[index++] = "CONTEXT_THREAD_AFFINITY";
contextProperties[index++] = "255";
contextProperties[index++] = "CONTEXT_CREATE_THREAD";
contextProperties[index++] = "1"; 
rc = Solclient.createContextForHandle(contextHandle, contextProperties);

Note: if you pass context properties to createContextForHandle(), you must include CONTEXT_CREATE_THREAD with a value of 1. (Its default is 0, meaning disabled, which is not supported).

3

Huh! I didn’t know that. Cool!

As an alternative, I usually handle my CPU affinity at the shell using taskset. That way I can change at runtime.

4

How did you calculate 255 ? I used 10 for using core 4 but don’t think it worked.

5

See the docs for the C API here: CCSMP API: Main Page (API Guide)
(Note, the JavaRTO API is a JNI wrapper around the C API… if you need pure Java, there is the new Java API, and the older JCSMP API)
It is a bitmask. So if you want core 4 (numbering starts at 0), you’ll want to set only the 5th bit from the right, or 0b00010000 , which is 16.
255 means 0b11111111 , or setting the mask so it can run on any core from 0-7.

6

Thanks @Aaron . Is it possible to busy spin? I saw if using shares memory there is an option to spin but I am using tcp protocol and couldn’t find any way to spin.

7

0x0000000000000010 is the bit mask I used as per CPU Affinity Mask Calculator for core 4. But after reading your response its clear that it is incorrect. Many thanks