Background:

Recently I used distcc to do distributed compilation, and found that some large files often could not be sent back to the local computer after compilation.
I checked the logs and code, and the reason for this is that Broken pipe appears when the server calls sendfile.

Problem

The problem can be summarized as:

1. client send a large input file (400M) to server
2. server receive input file and start to compile, which takes 300s
3. client call select() to wait server send output
4. server compile end and try send output. when call sendfile() will get error Broken pipe

Some of the triggering conditions are:

1. It can only be reproduced on a certain number of specific machines, but it is the same as the normal machine system version (Linux version 4.18.0-2.4.3), and I don’t know if there is any difference in system configuration.
2. Trigger 10 compilations at the same time, only 1-2 compilations fail.

Could it be caused by the buffer size? Because it only occurs when there are large files + simultaneous triggers