How To Gear Upward Java.Net.Socketexception: Also Many Files Opened Upward Java.Io.Ioexception Inwards Tomcat, Weblogic Server

Not many Java programmers knows that socket connections are treated similar files as well as they role file descriptor, which is a express resource. Different operating organization has unlike limits on reveal of file handles they tin give the sack manage. One of the mutual argue of java.net.SocketException: Too many files open inwards Tomcat, Weblogic or any Java application server is, likewise many clients connecting as well as disconnecting oftentimes at real curt bridge of time. Since Socket connexion internally role TCP protocol, which says that a socket tin give the sack rest inwards TIME_WAIT country for unopen to time, fifty-fifty afterwards they are closed. One of the argue to cash inwards one's chips along closed socket inwards TIME_WAIT country is to ensure that delayed packets reached to the corresponding socket. Different operating organization has unlike default fourth dimension to cash inwards one's chips along sockets inwards TIME_WAIT state, inwards Linux it's lx seconds, land inwards Windows is iv minutes. Remember longer the timeout, longer your closed socket volition cash inwards one's chips along file handle, which increase chances of java.net.SocketException: Too many files opened upwardly exception. 

This also means, if you lot are running Tomcat, Weblogic, Websphere or whatever other web server inwards windows machine, you lot are to a greater extent than prone to this mistake than Linux based systems e.g. Solaris or Ubuntu. 

By the way this mistake is same every bit java.io.IOException: Too many files opened upwardly exception, which is throw past times code from IO bundle if you lot endeavour to opened upwardly a novel FileInputStream or whatever flow pointing to file resource.

How to solve java.net.SocketException: Too many files open

Now, nosotros know that this mistake is coming because clients are connecting as well as disconnecting frequently. If that's seems odd to your application, you lot tin give the sack abide by the culprit customer as well as prohibit them from reconnecting from making a connection, only if that is something, your application may await as well as you lot wish to grip it on your side, you lot accept ii options :

1) Increase reveal of opened upwardly file handles or file descriptors per process.

2) Reduce timeout for TIME_WAIT country inwards your operating system

In UNIX based operating organization e.g. Ubuntu or Solaris, you lot tin give the sack role ascendence ulimit -a to abide by out how many opened upwardly file handles per procedure is allowed.

$ ulimit -a

core file size        (blocks, -c) unlimited

data seg size         (kbytes, -d) unlimited

file size             (blocks, -f) unlimited

open files                    (-n) 256

pipe size          (512 bytes, -p) 10

stack size            (kbytes, -s) 8192

cpu time             (seconds, -t) unlimited

max user processes            (-u) 2048

virtual memory        (kbytes, -v) unlimited

You tin give the sack run across that, opened upwardly files (-n) 256, which way entirely 256 opened upwardly file handles per procedure is allowed. If your Java program, retrieve Tomcat, weblogic or whatever other application server are Java programs as well as they run on JVM, exceeds this limit, it volition throw java.net.SocketException: Too many files opened upwardly error.

You tin give the sack alter this bound past times using ulimit -n to a larger reveal e.g. 4096, only produce it amongst suggest of UNIX organization administrator as well as if you lot accept dissever UNIX back upwardly team, than improve escalate to them.

Another of import matter to verify is that, your procedure is non leaking file descriptors or handles, good that's a deadening matter to abide by out, only you lot tin give the sack role lsof ascendence to cheque how many opened upwardly file handles is owned past times a item procedure in UNIX or Linux. You tin give the sack run lsof ascendence past times providing PID of your process, which you lot tin give the sack larn it from ps command.

Similarly, you lot tin give the sack alter TIME_WAIT timeout, only produce amongst consultation of UNIX support, every bit a actually depression fourth dimension means, you lot powerfulness immature lady delayed packets. In UNIX based systems, you lot ca n run across electrical flow configuration inwards /proc/sys/net/ipv4/tcp_fin_timeout file. In Windows based system, you lot tin give the sack run across this information inwards windows registry. You tin give the sack alter the TCP TIME_WAIT timeout inwards Windows past times next below steps :

1) Open Windows Registry Editor, past times typing regedit inwards run ascendence window

2) Find the fundamental HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\tcpip\Parameters

3) Add a novel fundamental value duet TcpTimedWaitDelay asa decimal as well as laid the desired timeout inwards seconds (60-240)

4) Restart your windows machine.

Remember, you lot powerfulness non accept permission to edit windows registry, as well as if you lot are non comfortable, improve non to produce it. Instead inquire Windows Network back upwardly team, if you lot accept any,  to produce that for you. Bottom business to fix java.net.SocketException: Too many files open, is that either increasing reveal of opened upwardly file handles or reducing TCP TIME_WAIT timeout. java.net.SocketException: Too many files open effect is also mutual among FIX Engines, where customer role TCP/IP protocol to connect amongst brokers FIX servers. Since FIX engines needs right value of incoming as well as outgoing sequence reveal to establish FIX session, and if customer tries to connect amongst a smaller sequence reveal than expected at brokers end, it disconnects the session immediately. If customer is good behind, as well as cash inwards one's chips along retrying past times increasing sequence reveal past times 1, it tin give the sack motility java.net.SocketException: Too many files open at brokers end. To avoid this, let's FIX engine cash inwards one's chips along rail of it's sequence number, when it restart. In short, "java.net.SocketException: Too many files open" can live on seen whatever Java Server application e.g. Tomcat, Weblogic, WebSphere etc, amongst customer connecting as well as disconnecting frequently.

Further Learning
Java Memory Management
Understanding the Java Virtual Machine: Memory Management
Understanding as well as Solving Java Memory Problems

Share this post