std.gc.disable not implemented or not working?

Frits van Bommel fvbommel at REMwOVExCAPSs.nl
Wed May 31 01:42:42 PDT 2006


Paolo Invernizzi wrote:
> Hi all,
> 
> DMD 0.159 win32, Why I don't see my memory exploding while the program 
> is running?
> 
> If It's a bug, I'll add it to the collector.
> 
> int main(char[][] argv) {
>     std.gc.disable();
>     for (int i=0; i < 1000000; i++) {
>         byte[] a = new byte[10000000];
>     }
> }

A bit more detailed test:

     D:\Temp>cat test.d
     import std.stdio;
     import std.gc;

     class Big
     {
         uint nr;
         byte[10_000_000] lots_of_data;
         this(uint nr_) {
             nr = nr_;
             writefln("             construct ", nr);
         }
         ~this() { writefln("destruct ", nr); }
     }

     void main(char[][] argv) {
         std.gc.disable();
         for (int i=0; i < 10; i++) {
             Big b = new Big(i);
         }
         writefln("Done.");
     }

     D:\Temp>dmd -run test.d
                  construct 0
                  construct 1
                  construct 2
                  construct 3
     destruct 3
                  construct 4
     destruct 4
                  construct 5
     destruct 5
                  construct 6
     destruct 6
                  construct 7
     destruct 7
                  construct 8
     destruct 8
                  construct 9
     Done.
     destruct 9

     D:\Temp>dmd
     Digital Mars D Compiler v0.159
     [[snip]]

(So to answer your question, your memory doesn't explode because the gc 
isn't really disabled)

And from the std.gc docs:

     void disable();
     void enable();
         disable() temporarilly disables garbage collection cycle, ...
         ... If the collector runs out of memory while it is disabled, 
it will throw an OutOfMemory exception. ...

I'd say the collector clearly doesn't conform to that behavior, so yes, 
that would be a bug.



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