Read text file fast, how?

[Jacob Carlborg via Digitalmars-d]

On 2015-07-27 14:03, Johan Holmberg via Digitalmars-d wrote:

> Back on MacOS again, I thought I should try to run "Instruments" on my
> program. I'm not familiar with the DMD source code, but I did the following:
>
> - downloaded the DMD source from Github + built it
> - rebuilt my program with this dmd
> - used Instruments (the MacOS profiler) on my program
>
> Two things showed up in Instruments that seemed suspicious, both in
> "stdio.d":
>
> 1) calls to "__tls_get_addr" inside readlnImpl" (taking 0.25s out of the
> total 1.69s according to Instruments). I added "__gshared" to the static
> variables "lineptr" and "n" to see if it had any effect (see below for
> results).
>
> 2) calls to "std.algorithm.endsWith" inside File.ByLine.Impl.popFront
> (taking 0.10s according to Intruments). I replaced it with a simpler
> test using inline code.
>
> The timings running my program normally (not using Instruments now),
> became as follows with the different versions of dmd:
>
> dmd unmodified: 1.59s
> dmd with change 1): 1.33s
> dmd with change 1+2): 1.22s
> C++ using <stdio.h>: 1.13s    (for comparison)

I recommend you also try using LDC. It has a better optimizer and is 
using native TLS on OS X.

-- 
/Jacob Carlborg