There is at least one race condition in the runtime. My larger application (multigrid algorithm for solving partial differential equations) crashes with a garbage collection error after some indeterministic time:
Duplicate large block deallocation of 0x13bc9000
Duplicate large block deallocation
I'm not sure where exactly this problem happens, but at least I
discovered something in GrowableIndexedMemoryChunk. The grow/shrink
method is not thread-safe, so a concurrent use is dangerous. Here is a
small program to reproduce it (dual core machine and X10_NTHREADS=2):
import x10.util.GrowableIndexedMemoryChunk;
public class LargeDealloc {
private static def adding(chunk:GrowableIndexedMemoryChunk[int]) {
while(true) {
val size = chunk.capacity();
chunk.grow(size+2);
}
}
public static def main(args:Array[String]):void {
val m = new GrowableIndexedMemoryChunk[int]();
finish {
async { adding(m); }
async { adding(m); }
}
}
}
Is that a bug or just wrong use of GrowableIndexedMemoryChunk?
My application does not use GrowableIndexedMemoryChunk directly, so the
runtime seems to have a bug anyways.
--
Andreas Zwinkau
Karlsruhe Institute of Technology (KIT)
Institut für Programmstrukturen und Datenorganisation (IPD)
Lehrstuhl Prof. Snelting
Adenauerring 20a
76131 Karlsruhe
Phone: +49 721 608 48351
Fax: +49 721 608 48457
Email: zwin...@kit.edu
Web: http://pp.info.uni-karlsruhe.de/person.php?id=107
KIT – University of the State of Baden-Wuerttemberg and
National Research Center of the Helmholtz Association
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