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At the beginning of today’s stress test, there were many exceptions, all of which were java.net.noroutetohostexception: cannot assign requested address

According to the information on the Internet, it is due to the exhaustion of the client connection port allocated by Linux and the failure to establish a socket connection. Although the socket is normally closed, the port is not released immediately, but is in time_ Wait state, wait for 60s by default before releasing.

Check the range of client connection ports supported by Linux, that is, 28232 ports

cat /proc/sys/net/ipv4/ip_ local_ port_ range

32768 – 61000

resolvent:

1. Reduce the waiting time after port release, which is 60 s by default and 15 ~ 30 s by modification

echo 30 >/proc/sys/net/ipv4/tcp_ fin_ timeout

2. Modify the TCP/IP protocol configuration by configuring/proc/sys/net/IPv4/TCP_ tw_ Reset, default to 0, modify to 1, release time_ The wait port is used for new connections.

echo 1 >/proc/sys/net/ipv4/tcp_ tw_ reuse

3. Modify the TCP/IP protocol configuration to recycle socket resources quickly. The default value is 0 and the value is 1

echo 1 >/proc/sys/net/ipv4/tcp_ tw_ recycle

Through the above three adjustments, the pressure test runs normally.