problem with gc?

I am writing a echoclient, as below: Ptr!Conn conn = connect("127.0.0.1",8881); ubyte[100] buf; for(int i=0; i<N; i++) { scope string str = format("%s",i); conn.write((cast(ubyte*)str.ptr)[0..str.length]); conn.read(buf[0..str.length]); n++; } conn.close(); When it loops about more than 100000 times,the throughput will fall from 60000request/second to 26request/second. If the code changes a little as below: scope string str = format("%s",10000); //changes to a constant It will runs normally with speed of 60000request/second. I test for 13minutes, everything seems well. What happened when the code changes a little? Who will give an explaination,Thanks a lot?

On Wednesday, 27 May 2015 at 05:51:21 UTC, zhmt wrote: > I noticed that the cpu% falls from 99% down to 4% as well when the throughput falls down. I tried again for several times, the cpu is still busy, 98.9%.

On Wednesday, 27 May 2015 at 05:48:13 UTC, zhmt wrote: > What happened when the code changes a little? Who will give an explaination,Thanks a lot? Yes, on the first sight it looks like your allocations in the loop make GC spend too much time. I don't think "scope" does anything here. Try adding "delete str;" to the end of the loop, it should do what your "scope" meant. I know it's deprecated but sometimes it's just right.

On Wednesday, 27 May 2015 at 05:48:13 UTC, zhmt wrote: > I am writing a echoclient, as below: > > Ptr!Conn conn = connect("127.0.0.1",8881); > ubyte[100] buf; > for(int i=0; i<N; i++) > { > scope string str = format("%s",i); > conn.write((cast(ubyte*)str.ptr)[0..str.length]); > conn.read(buf[0..str.length]); > n++; > } > conn.close(); > > > When it loops about more than 100000 times,the throughput will fall from 60000request/second to 26request/second. > > If the code changes a little as below: > > scope string str = format("%s",10000); //changes to a constant > > It will runs normally with speed of 60000request/second. I test for 13minutes, everything seems well. > > > > What happened when the code changes a little? Who will give an explaination,Thanks a lot? Have you tried to declare str in the upper scope ? --- Ptr!Conn conn = connect("127.0.0.1",8881); ubyte[100] buf; string str; for(int i=0; i<N; i++) { str = format("%s",i); conn.write(cast(ubyte[]) str); conn.read(buf[0..str.length]); n++; } conn.close(); --- And also you could try to surround the whole block with `GC.disable` and `GC.enable`. This would help to determine if the GC is involved: --- Ptr!Conn conn = connect("127.0.0.1",8881); GC.disable; ubyte[100] buf; string str; for(int i=0; i<N; i++) { str = format("%s",i); conn.write(cast(ubyte[]) str); conn.read(buf[0..str.length]); n++; } GC.enable; conn.close(); ---

On Wed, 27 May 2015 05:48:11 +0000 zhmt via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote: > I am writing a echoclient, as below: > > Ptr!Conn conn = connect("127.0.0.1",8881); > ubyte[100] buf; > for(int i=0; i<N; i++) > { > scope string str = format("%s",i); > conn.write((cast(ubyte*)str.ptr)[0..str.length]); > conn.read(buf[0..str.length]); > n++; > } > conn.close(); > > > When it loops about more than 100000 times,the throughput will fall from 60000request/second to 26request/second. > > If the code changes a little as below: > > scope string str = format("%s",10000); //changes to a constant > > It will runs normally with speed of 60000request/second. I test for 13minutes, everything seems well. > > > > What happened when the code changes a little? Who will give an explaination,Thanks a lot? what happend if you use sformat instead? Ptr!Conn conn = connect("127.0.0.1",8881); ubyte[100] buf; char[100] buf2; for(int i=0; i<N; i++) { auto str = sformat(buf2, "%s",i); conn.write((cast(ubyte*)str.ptr)[0..str.length]); conn.read(buf[0..str.length]); n++; } conn.close();

>> >> What happened when the code changes a little? Who will give an explaination,Thanks a lot? > > what happend if you use sformat instead? > > Ptr!Conn conn = connect("127.0.0.1",8881); > ubyte[100] buf; > char[100] buf2; > for(int i=0; i<N; i++) > { > auto str = sformat(buf2, "%s",i); > conn.write((cast(ubyte*)str.ptr)[0..str.length]); > conn.read(buf[0..str.length]); > n++; > } > conn.close(); @Daniel Kozák Thanks for reply. I have tried sformat, but it doesnt work: throughput falls down, and the cpu keeps busy.

@jklp > > And also you could try to surround the whole block with `GC.disable` and `GC.enable`. This would help to determine if the GC is involved: > > --- > Ptr!Conn conn = connect("127.0.0.1",8881); > GC.disable; > ubyte[100] buf; > string str; > for(int i=0; i<N; i++) > { > str = format("%s",i); > conn.write(cast(ubyte[]) str); > conn.read(buf[0..str.length]); > n++; > } > GC.enable; > conn.close(); > --- I have tried this, and throughput falls down as well too. Does this mean the gc is not involved? I am confused.