xrdp-chansrv stucks "Resource temporarily unavailable"

[metalefty]

Sometimes xrdp-chansrv stucks with CPU usage 100%.
I'm investigating the issue. Just for the record.

FreeBSD 12, xrdp 0.9.8.

recvmsg(11,0x7fffdfffdab8,0)                     ERR#35 'Resource temporarily unavailable'
recvmsg(11,0x7fffdfffdad8,0)                     ERR#35 'Resource temporarily unavailable'
select(17,{ 16 },0x0,0x0,{ 0.000000 })           = 1 (0x1)
recvfrom(16,"\0\0\0\0\M-4\^T\0\0",8,0,NULL,0x0)  = 8 (0x8)
recvfrom(16,"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"...,5292,0,NULL,0x0) = 5292 (0x14ac)
getrusage(RUSAGE_SELF,{ u=171.632692,s=3.573564,in=41,out=20 }) = 0 (0x0)
getrusage(RUSAGE_CHILDREN,{ u=0.000000,s=0.000000,in=0,out=0 }) = 0 (0x0)
select(14,0x0,{ 13 },0x0,{ 0.000000 })           = 0 (0x0)
select(14,0x0,{ 13 },0x0,{ 0.000000 })           = 0 (0x0)
getrusage(RUSAGE_SELF,{ u=171.643198,s=3.573564,in=41,out=20 }) = 0 (0x0)
getrusage(RUSAGE_CHILDREN,{ u=0.000000,s=0.000000,in=0,out=0 }) = 0 (0x0)
select(14,0x0,{ 13 },0x0,{ 0.000000 })           = 0 (0x0)
mmap(0x0,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) = 34574045184 (0x80cc61000)
mmap(0x0,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) = 34574049280 (0x80cc62000)
mmap(0x0,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) = 34574053376 (0x80cc63000)
mmap(0x0,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) = 34574057472 (0x80cc64000)
mmap(0x0,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) = 34574061568 (0x80cc65000)
mmap(0x0,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) = 34574065664 (0x80cc66000)
mmap(0x0,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) = 34574069760 (0x80cc67000)
mmap(0x0,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) = 34574073856 (0x80cc68000)
mmap(0x0,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) = 34574077952 (0x80cc69000)
mmap(0x0,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) = 34574082048 (0x80cc6a000)
select(14,0x0,{ 13 },0x0,{ 0.000000 })           = 0 (0x0)
select(15,{ 14 },0x0,0x0,{ 0.000000 })           = 0 (0x0)
select(16,{ 15 },0x0,0x0,{ 0.000000 })           = 0 (0x0)
select(17,{ 3 10 11 13 14 15 16 },{ 13 },0x0,0x0) = 2 (0x2)
select(4,{ 3 },0x0,0x0,{ 0.000000 })             = 0 (0x0)
select(14,{ 13 },0x0,0x0,{ 0.000000 })           = 1 (0x1)
recvfrom(13,"\0\0\0\0\^P\0\0\0",8,0,NULL,0x0)    = 8 (0x8)
recvfrom(13,"\a\0\0\0\b\0\0\0",8,0,NULL,0x0)     = 8 (0x8)
select(14,0x0,{ 13 },0x0,{ 0.000000 })           = 0 (0x0)
select(14,0x0,{ 13 },0x0,{ 0.000000 })           = 0 (0x0)
select(11,{ 10 },0x0,0x0,{ 0.000000 })           = 0 (0x0)
recvmsg(11,0x7fffdfffdab8,0)                     ERR#35 'Resource temporarily unavailable'
recvmsg(11,0x7fffdfffdad8,0)                     ERR#35 'Resource temporarily unavailable'
select(17,{ 16 },0x0,0x0,{ 0.000000 })           = 1 (0x1)
recvfrom(16,"\0\0\0\0\M-4\^T\0\0",8,0,NULL,0x0)  = 8 (0x8)
recvfrom(16,"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"...,5292,0,NULL,0x0) = 5292 (0x14ac)
getrusage(RUSAGE_SELF,{ u=171.658894,s=3.573564,in=41,out=20 }) = 0 (0x0)
getrusage(RUSAGE_CHILDREN,{ u=0.000000,s=0.000000,in=0,out=0 }) = 0 (0x0)
select(14,0x0,{ 13 },0x0,{ 0.000000 })           = 0 (0x0)

[jsorg71]

Is there any common thing you do that causes it? playing audio, clipboard copy, etc.

[metalefty]

I'm not sure yet. However, there was a misunderstanding. "Resource temporarily unavailable" does not equal to 100% CPU. At least on FreeBSD, chansrv always very frequently shows "Resource temporarily unavailable" but most case it works fine. No 100% CPU.

[metalefty]

Also #1435 is related to this.

[metalefty]

Solved by neutrinolabs/pulseaudio-module-xrdp#38