[Interest] Flush after QProcess::write to prevent it from filling writeBuffer
philip at c0xc.net
Sat Feb 18 01:16:02 CET 2023
I'm writing 1M chunks of data to a QProcess in a loop until all input
data is consumed. How do I wait after calling QProcess::write() until
all data has been sent to the process before calling write() again?
As documented, I have tried to call waitForBytesWritten(-1) after
write() but it only helps in the first iteration; then it does not seem
to block until all bytes are sent to the process. The result is that my
program uses almost 4G of RES memory if a 4G input file is being read
and the loop finishes in a second. Closing QProcess actually sends the
data to the process (takes minutes) and I don't see any progress.
Internally, Qt seems to use a QByteArray as writeBuffer and I could not
find where it checks if it exceeds a maximum size.
I believe QProcess storing 4 GB of data in an internal buffer is wrong
under any circumstances. Have I overlooked something in the
documentation? How do I turn this off?
I can provide a minimal example.
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