Yes, these too are for communication between processes. Only you don't use the network stack. This is a special feature of Unix-like operating systems.
DGRAM, unlike STREAM, does not know connection states. Therefore STREAM is comparable to a local TCP connection. Unix domain sockets exist in the file tree as special files. Access is controlled by file permissions, as is usual for files. Am Dienstag, den 31.03.2020, 14:29 +0200 schrieb André Warnier (tomcat/perl): > On 31.03.2020 14:20, Mark Thomas wrote: > > On 31/03/2020 11:20, Aditya Kumar wrote: > > > Tomcat 9.0.30 on Windows Server 2012 / Java 1.8 > > > > > > I've noticed on a freshly installed version of tomcat 9, upon > > > startup there > > > are several connections to and from localhost on different ports > > > > > > For example on my tomcat server there are 4 connections to and > > > from > > > localhost (output from netstat) > > > > > > > > > TCP 0.0.0.0:8080 0.0.0.0:0 LISTENING > > > 3972 > > > > > > TCP 127.0.0.1:55618 127.0.0.1:55619 ESTABLISHED > > > 3972 > > > > > > TCP 127.0.0.1:55619 127.0.0.1:55618 ESTABLISHED > > > 3972 > > > > > > TCP 127.0.0.1:55620 127.0.0.1:55621 ESTABLISHED > > > 3972 > > > > > > TCP 127.0.0.1:55621 127.0.0.1:55620 ESTABLISHED > > > 3972 > > > > > > TCP [::]:8080 [::]:0 LISTENING > > > 3972 > > > > > > These can grow to a large number (several thousand) on a busy > > > system. What > > > are these connections used for? What caused them? What thread are > > > they > > > attributed to? > > > > The Java NIO implementation on Windows uses TCP for intra-process > > signalling. It opens a pair of self-connected sockets for every > > Selector. > > > > Mark > > > > While we're at it, under Linux, are the following for a similar > reason ? > > output of : netstat -pan | grep 27514 (tomcat's JVM PID = 27514) > [...] > unix 2 [ ] STREAM CONNECTED 167427210 > 27514/java > unix 2 [ ] STREAM CONNECTED 167423436 > 27514/java > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
