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Date: Wed, 25 Feb 2015 16:54:08 +1100
Subject: Re: Are threads bad? - was: Future of Pypy?
From: Chris Angelico <rosuav@gmail.com>
Cc: "python-list@python.org" <python-list@python.org>
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Xref: csiph.com comp.lang.python:86378

On Wed, Feb 25, 2015 at 4:46 PM, Marko Rauhamaa <marko@pacujo.net> wrote:
> Marcos Almeida Azevedo <marcos.al.azevedo@gmail.com>:
>
>> Synchronized methods in Java really makes programming life simpler.
>> But I think it is standard practice to avoid this if there is a
>> lighter alternative as synchronized methods are slow. Worse case I
>> used double checked locking.
>
> I have yet to see code whose performance suffers from too much locking.
> However, I have seen plenty of code that suffers from anomalies caused
> by incorrect locking.

Uhh, I have seen *heaps* of code whose performance suffers from too
much locking. At the coarsest and least intelligent level, a database
program that couldn't handle concurrency at all, so I wrote an
application-level semaphore that stopped two people from running it at
once. You want to use that program? Ask the other guy to close it.
THAT is a performance problem. And there are plenty of narrower cases,
where it ends up being a transactions-per-second throughput limiter.

ChrisA