linux - [Solved-5 Solutions] Maximum number of threads per process in Linux - ubuntu - red hat - debian - linux server - linux pc

What is the maximum number of threads that can be created by a process under Linux?

cat /proc/sys/kernel/threads-max

The default is the number of memory pages/4. You can increase this like:

echo 100000 > /proc/sys/kernel/threads-max

There is also a limit on the number of processes (and hence threads) that a single user may create.

Linux doesn't have a separate threads per process limit.

Linux implements max number of threads per process indirectly

number of threads = total virtual memory / (stack size*1024*1024)

Thus, the number of threads per process can be increased by increasing total virtual memory or by decreasing stack size.

Total Virtual Memory: ulimit -v (default is unlimited, thus you need to increase swap memory to increase this)

Total Stack Size: ulimit -s (default is 8Mb)

ulimit -s newvalue

ulimit -v newvalue

Checking the current number of threads used

The following command will output the number of processes for the myfasuser (example) user. Note: Threads are counted as processes in linux

top -b -H -u myfasuser -n 1 | wc -l

If the number is less than 200 try without the -H flag as the Thread toggle may have already been set in top

top -b -u myfasuser -n 1 | wc -l

The highest of these 2 outputs indicates the number of myfasuser processes A base line Cafex installation will typically use around 700 threads in a quiescent state and this figure will rise over time with traffic and the full product set deployed.

To retrieve it:

cat /proc/sys/kernel/threads-max

To set it:

echo 123456789 > /proc/sys/kernel/threads-max

Linux doesn't use the virtual memory to calculate the maximum of thread, but the physical ram installed on the system

max_threads = totalram_pages / (8 * 8192 / 4096);

kernel/fork.c

/* The default maximum number of threads is set to a safe
 * value: the thread structures can take up at most half
 * of memory.
 */
max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);

• Thread max is different between every system, because the ram installed can be from different sizes, I know Linux doesn't need to increase the virtual memory, because on 32 bit we got 3 GB for user space and 1 GB for the kernel, on 64 bit we got 128 TB of virtual memory, that happen on Solaris, if you want increase the virtual memory you need to add swap space.