Message passing between threads: Java 4 times faster than D

Marco Leise Marco.Leise at
Thu Feb 9 02:11:20 PST 2012

Am 09.02.2012, 10:06 Uhr, schrieb Nicolae Mihalache <xpromache at>:

> Hello,
> I'm a complete newbie in D and trying to compare with Java. I
> implemented  a simple test for measuring the throughput in message
> passing between threads. I see that Java can pass about 4mil
> messages/sec while D only achieves 1mil/sec. I thought that D should
> be faster.
> The messages are simply integers (which are converted to Integer in  
> Java).
> The two programs are attached. I tried compiling the D version with
> both dmd and gdc and various optimization flags.
> mache

I cannot give you an explanation, just want to say that a message in  
std.concurrency is also using a wrapper (a 'Variant') + a type field  
(standard, priority, linkDead). So you effectively have no optimization  
for int, but the same situation as in Java.
The second thing I notice is that std.concurrency uses a double linked  
list implementation, while you use an array in the Java version, which  
results in no additional node allocations.

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