PHP-FPM processes hang in UFS-state

[Jon Schneider]

I think this might be a job for DTrace which I don’t know enough to exactly what to do but you probably want to trace use of all those functions you see in your traces and everything in UFS. Hint: do not send  DTrace output to something on UFS !

You might also want to create a smaller test  case to induce the problem quickly.

Be interesting to hear what you discover.

Jon

> On 24 Oct 2020, at 13:28, Christos Chatzaras <chris at cretaforce.gr> wrote:
> 
> This issue happened in 3 different servers the last months.
> 
> Some PHP-FPM processes hang in UFS-state.
> 
> The websites that cause the hang are all Prestashop and it's related to their var/cache files (I believe it happens when they clear the cache and the files are regenerated).
> 
> 
> This is a php-fpm process that hang:
> 
> procstat -kk 73548
> 
>  PID    TID COMM                TDNAME              KSTACK
> 73548 100630 php-fpm             -                   mi_switch+0xe2 sleepq_wait+0x2c sleeplk+0x185 lockmgr_xlock_hard+0x1f5 __lockmgr_args+0x2bf ffs_lock+0xa5 VOP_LOCK1_APV+0x7c _vn_lock+0x44 vget+0x4a vfs_hash_get+0xb0 ffs_vgetf+0x3f softdep_sync_buf+0xbee ffs_syncvnode+0x26f ffs_truncate+0x71b ufs_direnter+0x5f8 ufs_makeinode+0x5fb ufs_create+0x34 VOP_CREATE_APV+0x76 
> 
> 
> procstat -kk -a :
> 
> https://www.coderz.gr/ufs/procstat.txt
> 
> 
> mount | grep home :
> 
> https://www.coderz.gr/ufs/mount.txt
> 
> 
> dumpfs /dev/mirror/gm0p7 :
> 
> https://www.coderz.gr/ufs/dumpfs.txt
> 
> 
> I have to force reboot the server as /home is not possible to clean unmount. Then I run fsck which fixes some issues because of the unclean reboot. Then I run fsck again that shows no errors. Then I mount /home and first rename the cache folders and finally delete var/cache and allow it to regenerate prestashop files. But the same issue happens again after few days.
> 
> 
> Any idea how to troubleshoot it?
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