Write on sockets blocking for long periods of time on writes












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Here is the scenario where i am seeing writes on TCP sockets getting blocked for long periods of time




  1. Client (curl) is downloading a large file at slow speed, I can reproduce this by using curl --limit-rate 1k option


  2. Server (running on Ubuntu 16.04.5 LTS) does writes on socket in a loop


  3. In tcp-dump traces, I do see that TCP window of client becomes zero and server is sending ~ 1 KB data/ sec


  4. The writes blocks for ~ 60 seconds and then allows writes of abt 60 K in burst and then blocks again for 60+ seconds


  5. Assuming that send buffer is of fixed size, I would have assumed that writes would block for 1 second and allow write of 1k and then again block for 1 secs , i.e. allow write of 1k every second instead of 60+k every 60 seconds in bursts



Does any one know the reasoning on why i am seeing this behavior? I can see this behavior by looking at strace output










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    0















    Here is the scenario where i am seeing writes on TCP sockets getting blocked for long periods of time




    1. Client (curl) is downloading a large file at slow speed, I can reproduce this by using curl --limit-rate 1k option


    2. Server (running on Ubuntu 16.04.5 LTS) does writes on socket in a loop


    3. In tcp-dump traces, I do see that TCP window of client becomes zero and server is sending ~ 1 KB data/ sec


    4. The writes blocks for ~ 60 seconds and then allows writes of abt 60 K in burst and then blocks again for 60+ seconds


    5. Assuming that send buffer is of fixed size, I would have assumed that writes would block for 1 second and allow write of 1k and then again block for 1 secs , i.e. allow write of 1k every second instead of 60+k every 60 seconds in bursts



    Does any one know the reasoning on why i am seeing this behavior? I can see this behavior by looking at strace output










    share|improve this question







    New contributor




    Harish Rawat is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      0








      Here is the scenario where i am seeing writes on TCP sockets getting blocked for long periods of time




      1. Client (curl) is downloading a large file at slow speed, I can reproduce this by using curl --limit-rate 1k option


      2. Server (running on Ubuntu 16.04.5 LTS) does writes on socket in a loop


      3. In tcp-dump traces, I do see that TCP window of client becomes zero and server is sending ~ 1 KB data/ sec


      4. The writes blocks for ~ 60 seconds and then allows writes of abt 60 K in burst and then blocks again for 60+ seconds


      5. Assuming that send buffer is of fixed size, I would have assumed that writes would block for 1 second and allow write of 1k and then again block for 1 secs , i.e. allow write of 1k every second instead of 60+k every 60 seconds in bursts



      Does any one know the reasoning on why i am seeing this behavior? I can see this behavior by looking at strace output










      share|improve this question







      New contributor




      Harish Rawat is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.












      Here is the scenario where i am seeing writes on TCP sockets getting blocked for long periods of time




      1. Client (curl) is downloading a large file at slow speed, I can reproduce this by using curl --limit-rate 1k option


      2. Server (running on Ubuntu 16.04.5 LTS) does writes on socket in a loop


      3. In tcp-dump traces, I do see that TCP window of client becomes zero and server is sending ~ 1 KB data/ sec


      4. The writes blocks for ~ 60 seconds and then allows writes of abt 60 K in burst and then blocks again for 60+ seconds


      5. Assuming that send buffer is of fixed size, I would have assumed that writes would block for 1 second and allow write of 1k and then again block for 1 secs , i.e. allow write of 1k every second instead of 60+k every 60 seconds in bursts



      Does any one know the reasoning on why i am seeing this behavior? I can see this behavior by looking at strace output







      networking






      share|improve this question







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      Harish Rawat is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      share|improve this question







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      Harish Rawat is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      asked Jan 21 at 18:11









      Harish RawatHarish Rawat

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