Berkeley CSUA MOTD:Entry 43954
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2025/05/24 [General] UID:1000 Activity:popular
5/24    

2006/8/9-14 [Computer/Networking, Computer/SW/OS/Linux] UID:43954 Activity:nil
8/9     Linux question.  We have a simple server that recieves TCP/IP
        connections concurrently with a threadpool, creating new threads
        as necessary.  It's showing a weird performance quirk where, if
        you increase the number of concurrent connections, the connection
        time increases slowly, from .1s.  At 16 connections it's
        about .2s.  However, the 17th connection takes 1.2s, a large
        jump.  The connection times continue increasing slowly from
        there, although there are little jumps at 48 and similar
        multiples of 16. slowly.  Is there some magic kernel number 16,
        above with establishing a TCP/IP connection takes a long time?
        \_ Stupid question, does your threadpool have a max number of
           threads?
           \_ Yes, but it's 1024, which is actually higher than the kernel
              seems to be able to generate.
              \_ Java threads?  pthreads?
                 \_ pthreads, it's all C or C++ code on chaos Linux,
                    (although we were able to duplicate the problem on
                    RedHat,)
                    \- i dunno what the linux equiv of tcp_conn_hash_size
                       is, but i'd personally be interested if changing
                       bumping that up changes the behavior.
                       is, but i'd personally be interested if bumping that
                       up changes the behavior.
           \_ No. -proud American
2025/05/24 [General] UID:1000 Activity:popular
5/24    

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