-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Frank,
On 3/31/20 09:30, Frank Tornack wrote: > 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. Yup. It's helpful to see the column headers for your netstat output, André: > Proto RefCnt Flags Type State I-Node > PID/Program name Path unix 2 [ ] STREAM > CONNECTED 167427210 27514/java unix 2 [ ] STREAM > CONNECTED 167423436 27514/java Each "unix" protocol-connection (UNIX domain socket) has an associated inode on the root filesystem, but no path. Basically, it's magic. :) The nice thing on *NIX is that even though there is a hand-wavy device supporting NIO for Java, it doesn't consume pairs of ports (which are a limited resource; see our recent discussion on the limits of TCP port numbers). - -chris > 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 > -----BEGIN PGP SIGNATURE----- Comment: Using GnuPG with Thunderbird - https://www.enigmail.net/ iQIzBAEBCAAdFiEEMmKgYcQvxMe7tcJcHPApP6U8pFgFAl6DUP8ACgkQHPApP6U8 pFgxiBAAkmLWWhwvrLW+RJ5j3ZKEu5cXQ0x3/zsMpFuP2GPok1lemXixa8T91lSO eGg6W80DhVb76tDJl4Akt3L8ejN2XNgSxnHgGfEiCvTughYryAmHNXxze3ZMj4BQ pvIO8hCc1nSlti71h6C2vEGYLnwkHyMulIolYaHP+SxKX7PSxXcfo4zD6vvpTvnO U5Hrk7H8JjXCANrd8LsChN8w8AkWMUJpu/TUXFYy8bWEN9Ui7SdGqfa1t+pwnl8+ JZqO1moBP9WcMA/XR1msWIbkA8B1r+ICWqlqcdGlvkXrHzkiALdqpxy0WiKAs1Tn J+uPp0mAGpXRU3NGibr5NMtHLQ3Kl+X821yHYjF0XjqFwjLgvQNrmdYwblqFCUPB 9sIVr6CuWAxPM61QZ9Bi9fT4MrIA6f8iSEa7BDJmUWhARPQMKn6fjIOMd8Cok882 cGU1WT8O2SrtQV+y7wJbbq4aP4e6vRi/nSqI2hlSFdTBfD1Grj+t5JPHg35AafR4 +6qum9rVF3AKf47UoJFrXG9smWLkUVVsJuZbdHLofmQEV0ovOMzAPx2GR9oSR2/M sCxdUdqrhEW08wwYwIOV59vNa9pn/X/SOEre09yLH/GMV3H03CiQni616luWPrQt 0BzFi4+8TPVzKCaq88ThyjJnEMuDU9RNeS7IHScHTXQa6rflB7E= =q/Fd -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
