Posted Mon, 4 Nov 2019 21:05:52 +0100 in reply to StdFileStream really slow
Am 03.11.2019 um 16:04 schrieb StdFileStream really slow:
I tried to serve a file via HTTP (but serveStaticFiles does not match my requirements). My first try was to use vibe.stream.stdio.StdFileStream, but this was very slow with speed like 350kB/s.
Then I looked into the implementation of sendFile and switched to vibe.core.file.FileStream, which serves the same 100MB file in an instant.
Everything from and to localhost.
Where does the difference come from and what is StdFileStream good for?
StdFileStream is a compromise implementation using threads to support
blocking file descriptors when nothing else is available. If possible,
FileStream is always the preferred implementation.
However, 350 kB/s is definitely far slower than it should be. The first
thing that I noticed was that the default buffer size is rather small
with just 2 kB, it should be at least 64 kB, ideally 256 kB or more.
Another thing is that the data is copied up to three times - once into a
temporary read buffer, then into the
TaskPipe buffer, and finally into
the user target buffer.
Finally, reading from a
StdFileStream is implemented by reading a
single character at a time to ensure that data is read in real-time for
interactive pipes (terminal input). For actual disk files this is
obviously a performance hazard and there should probably a flag in the
constructor to control this behavior.