Not sure if others have the same problem, but my FreeBSD Sync installation always takes 100% CPU load after it's running for a while. The web UI can't be loaded at all.
I've already upgraded Sync to 2.3.8
In top it shows
PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND
79970 btsync 7 22 0 1065M 809M umtxn 3 553:54 100.00% btsync
umtxn means Kernel Lock.
So I ran
# procstat -k 79970
PID TID COMM TDNAME KSTACK
79970 100367 btsync - mi_switch sleepq_catch_signals sleepq_timedwait_sig _sleep umtxq_sleep do_wait __umtx_op_wait_uint_private amd64_syscall Xfast_syscall
79970 100592 btsync - mi_switch sleepq_catch_signals sleepq_timedwait_sig _sleep umtxq_sleep do_wait __umtx_op_wait_uint_private amd64_syscall Xfast_syscall
79970 100594 btsync - mi_switch sleepq_catch_signals sleepq_timedwait_sig _sleep kern_kevent_fp kern_kevent sys_kevent amd64_syscall Xfast_syscall
79970 100602 btsync - mi_switch sleepq_catch_signals sleepq_timedwait_sig _sleep umtxq_sleep do_wait __umtx_op_wait_uint_private amd64_syscall Xfast_syscall
79970 100603 btsync - mi_switch sleepq_catch_signals sleepq_timedwait_sig _sleep umtxq_sleep do_wait __umtx_op_wait_uint_private amd64_syscall Xfast_syscall
79970 100605 btsync - <running>
79970 100607 btsync - mi_switch sleepq_catch_signals sleepq_wait_sig _sleep umtxq_sleep do_lock_umutex __umtx_op_wait_umutex amd64_syscall Xfast_syscall
Looks like a thread is locked.
In the log, there're may SyncSocket errors. For example:
[20160710 13:12:53.238] SyncSocket[0x0000000827bf4480]: an error has occurred - code: 61, message: "Connection refused"
ZFS has been enabled in my Freebsd installation. Around 40 folders have been shared.