What is the reason for increasing time_wait connection in java?

Question

What is the reason for increasing time_wait connection in java?

 class LogWriter implements Runnable {

Socket client;

private static ThreadLocal<Date> date = new ThreadLocal<Date>() {
@Override
protected Date initialValue() {
    return new Date();
};
};

private static ThreadLocal<SimpleDateFormat> formatter = new ThreadLocal<SimpleDateFormat>() {
@Override
protected SimpleDateFormat initialValue() {
    return new SimpleDateFormat("yyyy_MM_dd");
};
};

public LogWriter(Socket client) {
this.client = client;
}

public void run() {
try {
    write(this.client.getInputStream(), new File(
        CentralizedLogging.logsDir + File.separator
            + client.getInetAddress().getHostName() + "_"
            + getFormattedDate() + ".log"));
    this.client.close();
} catch (Exception e) {
    try {
    e.printStackTrace();
    write(new ByteArrayInputStream(e.getMessage().getBytes()),
        new File(CentralizedLogging.logsDir + File.separator
            + "centralLoggingError.log"));
    } catch (IOException io) {

    }
}
}

  public synchronized void write(InputStream in, File file)
    throws IOException {
RandomAccessFile writer = new RandomAccessFile(file, "rw");
writer.seek(file.length()); // append the file content into existing if it not exist creating a new one.
writer.write(read(in));
writer.close();
}

public static byte[] read(InputStream in) throws IOException {
ByteArrayOutputStream out = new ByteArrayOutputStream();
int read = -1;
byte[] buffer = new byte[1024];
read = in.read(buffer);
do {
    out.write(buffer, 0, read);
} while((read = in.read(buffer)) > -1);
return out.toByteArray();
}

Main method

   public static void main(String[] args) throws InterruptedException,
    IOException {
// CentralizedLogging centralLogServer = new CentralizedLogging(args[0],Integer.parseInt(args[1]));
// new Thread(centralLogServer).start();
long start = System.currentTimeMillis() + 1000 * 20 * 60;
while(start >= System.currentTimeMillis()) {
    Socket client = new Socket("bharathi-1397", 10000);
    OutputStream os = client.getOutputStream();
    DataOutputStream outToServer = new DataOutputStream(os);
    outToServer
        .write("Centralized Logging is working......".getBytes());
    client.close();
}
}

I close the connection correctly. But time_wait connections are increasing. I took a snapshot from my terminal. I posted one part of it. Am I missing something?

 tcp6       0      0 127.0.0.1:46146         127.0.0.1:10000         TIME_WAIT   -               
 tcp6       0      0 127.0.0.1:57645         127.0.0.1:10000         TIME_WAIT   -               
 tcp6       0      0 127.0.0.1:47961         127.0.0.1:10000         TIME_WAIT   -               
 tcp6       0      0 127.0.0.1:56716         127.0.0.1:10000         TIME_WAIT   -               
 tcp6       0      0 127.0.0.1:49469         127.0.0.1:10000         TIME_WAIT   -               
 tcp6       0      0 127.0.0.1:54078         127.0.0.1:10000         TIME_WAIT   -               
 tcp6       0      0 127.0.0.1:51626         127.0.0.1:10000         TIME_WAIT   -               
 tcp6       0      0 127.0.0.1:50143         127.0.0.1:10000         TIME_WAIT   -               
 tcp6       0      0 127.0.0.1:59214         127.0.0.1:10000         TIME_WAIT   -               
 tcp6       0      0 127.0.0.1:54192         127.0.0.1:10000         TIME_WAIT   -               
 tcp6       0      0 127.0.0.1:53436         127.0.0.1:10000         TIME_WAIT   -               
 tcp6       0      0 127.0.0.1:54547         127.0.0.1:10000         TIME_WAIT   -               
 tcp6       0      0 127.0.0.1:55032         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:51273         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:48381         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:47532         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:56811         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:55293         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:56664         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:49242         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:51225         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:59265         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:59378         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:47997         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:47955         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:59453         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:48092         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:52462         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:59579         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:54921         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:55675         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:51140         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:57321         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:51656         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:54740         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:53600         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:59862         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:54766         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:59062         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:55702         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:50942         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:53732         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:52757         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:56430         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:49179         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:48689         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:53313         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:51161         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:57033         127.0.0.1:10000         TIME_WAIT   -               
tcp6       0      0 127.0.0.1:58607         127.0.0.1:10000         TIME_WAIT   -

Does this cause problems on my server? What is the reason for this ?,

+3

java serversocket

kannanrbk May 23 '12 at 18:48

source share

1 answer

Gray · Accepted Answer · 2012-05-23T19:20:11+0000

I close the connection correctly, but the time_wait connections increase. Did I miss something?

TIME_WAITis used by the kernel to ensure that your TCP stream does not reuse a port that can still send packets from a remote location. Typically, time TIME_WAITequals doubles the maximum age of packets on network settings.

, TIME_WAIT, - , . grep TIME_WAIT, , . , , .

, , close(). TIME_WAIT , . . TCP TIME_WAIT .

, ( ), , - . , TIME_WAIT .

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, close() first @kannan? , , , "" . , EOF, " " .

, , try ... finally . - :

public void run() {
    try {
        write(this.client.getInputStream(), new File(
            CentralizedLogging.logsDir + File.separator
            + client.getInetAddress().getHostName() + "_"
            + getFormattedDate() + ".log"));
    } catch (Exception e) {
        try {
            e.printStackTrace();
            write(new ByteArrayInputStream(e.getMessage().getBytes()),
                new File(CentralizedLogging.logsDir + File.separator
                + "centralLoggingError.log"));
        } catch (IOException io) {
        }
    } finally {
        // always close in the finally
        this.client.close();
    }
}

What is the reason for increasing time_wait connection in java?

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