Speed up reading from in_stream #983
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This change means that we don't delay reading the input stream when there is still data available to read from it. This provides a significant speed improvement to scripts which are passing a populated stream of data, rather than awaiting user input from stdin. See pyinvoke#774
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I observed minor performance improvements by using this larger chunk read size. Python's docs describe `io.DEFAULT_BUFFER_SIZE` as: > An int containing the default buffer size used by the module’s > buffered I/O classes. open() uses the file’s blksize ... The docs on `blksize` say: > “Preferred” blocksize for efficient file system I/O. Writing to a file > in smaller chunks may cause an inefficient read-modify-rewrite. References: - https://docs.python.org/3/library/io.html#io.DEFAULT_BUFFER_SIZE - https://docs.python.org/3/library/os.html#os.stat_result.st_blksize
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By only sleeping when the input stream is waiting, this change ensures that we don't delay when there is still data available to read.
This provides a significant speed improvement to scripts which are passing a populated stream of data, rather than awaiting user input from stdin.
I had to modify an existing test to ensure that it continued to see
sleeps.I have also changed the default chunk read size to match Python's default, which is the "“Preferred” blocksize for efficient file system I/O." (Of course, I'm happy to revert this if it makes the PR more palatable.)
Fixes #774