Have you tried using the same handle for both STDOUT and STDERR?

Alternatively, if you're using win32, there is an system api to control the buffer size (local and remote) of pipes. You may be able to reduce the buffer size to 0 and so achieve some level of immediacy.

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In reply to Re: [UPDATED] How to autoflush streams (i.e. open3 calls) by BrowserUk
in thread [UPDATED] How to autoflush streams (i.e. open3 calls) by rapide

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