We are running on a Wilfly 9.0.1, Java 8,  Solaris sparc. After 10 hours of uptime the application reaches  aprox 9000 open file descriptors. The majority of these descriptors (7000 out of 9000 are of FIFO type) as below:

java    33475 jboss 1448u  FIFO 0xc414ba182e40       0t1 451289989 (fifofs) PIPE->0xc414ba182ed0

java    33475 jboss 1449u  FIFO 0xc414ba182ed0       0t1 451289989 (fifofs) PIPE->0xc414ba182e40

java    33475 jboss 1450u  VCHR       175,5220            91750404 /devices/pseudo/poll@0:poll (COMMON)

java    33475 jboss 1451u  FIFO 0xc417b0352580       0t1 451289990 (fifofs) PIPE->0xc417b0352610

java    33475 jboss 1452u  FIFO 0xc417b0352610       0t1 451289990 (fifofs) PIPE->0xc417b0352580

java    33475 jboss 1453u  VCHR       175,5221            91750404 /devices/pseudo/poll@0:poll (COMMON)

java    33475 jboss 1454u  FIFO 0xc4159c9f0160       0t1 451289991 (fifofs) PIPE->0xc4159c9f01f0

java    33475 jboss 1455u  FIFO 0xc4159c9f01f0       0t1 451289991 (fifofs) PIPE->0xc4159c9f0160

java    33475 jboss 1456u  VCHR       175,5222            91750404 /devices/pseudo/poll@0:poll (COMMON)

The limit of max file descriptors is set to 32000.

When the threshold of aprox 9000 is reached we experience side effects as other application hanging when invoking a rest web service exposed by this application.

With the reaching of this threshold we also see IPv4 CLOSE_WAIT connections.

Do you have any hints on how to investigate this, how to determine the provenience of these file descriptors (FIFO).