For large files like this, the read heads will still be "jumping around" anyway, because unless you just de-fragged your disk, the file is likely to be physically spread out.

Yes I know. But, if you are trying to read from 5 files concurrently, your read heads are going to be jumping around far more than if you are only reading from one file. (All else being equal.)

And depending upon your OS and filing system, 5 concurrent readers means far less system cache devoted to each file, which will further decrease throughtput. Then there are factors such as on disk caching and myriad other hardware and software related factors.

But as a cojent, if simplified, explanation of why multithreading can have a negative affect on the throughput of the OPs application, I think my post stands on it's own.

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

In reply to Re^3: Threads Doubt by BrowserUk
in thread Threads Doubt by Anonymous Monk

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