What it could mean? Should our client worry about this?

2017-04-04 09:02:20 UserLoginVc 12965
2017-04-04 09:02:20 /THREAD(2) unexpected error from select(), retval=-1, errno=0 (Unknown error)
2017-04-04 09:02:20 /THREAD(2) unexpected error from select(), retval=-1, errno=0 (Unknown error)
2017-04-04 09:02:20 /THREAD(2) unexpected error from select(), retval=-1, errno=0 (Unknown error)
2017-04-04 09:02:20 GlobalUserPasswdVc 4