Re: Extreme memory usage when `synchronized( this )` is used

[tcak via Digitalmars-d-learn]

On Monday, 11 May 2015 at 09:09:09 UTC, tcak wrote:

[code]
import std.stdio;

class Connection{
        private void other() shared{}

        public void close() shared{
                synchronized( this ){
                        other();
                }
        }

        public void hasData() shared{ writeln("Has Data"); }
}

void main() {
        for(long i=0; i < 250_000_000; ++i){
                auto conn = new shared Connection();

                conn.hasData();

                conn.close();
        }
}
[/code]

With this code, memory usage of program is increasing very fast. In about 10 seconds, it reached 100MB for me.

If I comment out `synchronized( this )` line with its parentheses, OR remove `(this)` from it, it suddenly turns normal. Very little memory usage.

What's happening? Is object instance being stored somewhere at each iteration?

--

I tried the same thing by creating synchronisation object instead of object itself as blow, still usage lots of memory.

[code]
import std.stdio;

class Connection{
        private Object syncObject;

        public this() shared{
                syncObject = new shared Object();
        }

        private void other() shared{}

        public void close() shared{
                synchronized( syncObject ){
                        other();
                }
        }

        public void hasData() shared{ writeln("Has Data"); }
}

void main() {
        for(long i=0; i < 250_000_000; ++i){
                auto conn = new shared Connection();

                conn.hasData();

                conn.close();
        }
}
[/code]

I use DMD 2.067.1 on Ubuntu 14.04 64 bit