[Jack-Devel] Jack: "Too many servers already active"

Yuri yuri at rawbw.com
Wed Aug 23 03:17:18 CEST 2017

On 08/22/17 17:45, Malik Costet wrote:
> Do you have any indication which filesystem/location JACK would be
> looking for the condition? Could it also be a case of flag misuse?

Looking again, ENOSPC is returned by jack_register_server. 
jack_register_server simulates the error ENOSPC when it can't find a 
free slot in the shared memory table.

The table allows up to MAX_SERVERS=8 servers. It appears that shared 
memory isn't deleted when the last process using it quits, and it got 
polluted with bogus data.

Jack appears to use shared memory at "/jack-shm-registry".

I recently saw such situation on FreeBSD with another app, 
supercollider. Creating shared memory was failing there, no apps were 
using it. Not sure if this is a bug in kernel that it isn't 
automatically free when users die. But Jack could at least test if pids 
registered there are alive.

In short, no quick solution for you. Jack needs to be fixed. It needs to 
detect that pids recorded in the table are dead and invalidate them.

I propose the following fix.

The line:

 > if (jack_shm_header->server[i].pid == 0) {

changes to

 > if (jack_shm_header->server[i].pid == 0 || 
kill(jack_shm_header->server[i].pid, 0) != 0) {


More information about the Jackaudio mailing list