Or, even better, why not just using the next value from the "seeder"
sequence for the initial value of "secondary" seed and avoid interaction
with TLR's main seed/probe:
diff -r 5b45a5efe417
src/share/classes/java/util/concurrent/ThreadLocalRandom.java
--- a/src/share/classes/java/util/concurrent/ThreadLocalRandom.java Tue
May 20 10:11:23 2014 +0400
+++ b/src/share/classes/java/util/concurrent/ThreadLocalRandom.java Thu
Jun 19 10:45:25 2014 +0200
@@ -1034,8 +1034,7 @@
r ^= r << 5;
}
else {
- localInit();
- if ((r = (int)UNSAFE.getLong(t, SEED)) == 0)
+ if ((r = (int)mix64(seeder.getAndAdd(SEEDER_INCREMENT))) == 0)
r = 1; // avoid zero
}
UNSAFE.putInt(t, SECONDARY, r);
Regards, Peter
On 06/19/2014 10:37 AM, Peter Levart wrote:
Hi,
I noticed an inconsistency in calling TLR.localInit() method.
Everywhere it's called conditionaly if thread-local "probe" is zero
except in TLR.nextSecondarySeed() where it's called if "secondary"
seed is zero. This re-initializes the "probe" and "seed" even though
they might have already been initialized. It's not a big deal, because
this happens at most once per thread, but it would be more consistent
to call localInit() conditionaly, I think:
diff -r 5b45a5efe417
src/share/classes/java/util/concurrent/ThreadLocalRandom.java
--- a/src/share/classes/java/util/concurrent/ThreadLocalRandom.java
Tue May 20 10:11:23 2014 +0400
+++ b/src/share/classes/java/util/concurrent/ThreadLocalRandom.java
Thu Jun 19 10:34:18 2014 +0200
@@ -1034,7 +1034,8 @@
r ^= r << 5;
}
else {
- localInit();
+ if (UNSAFE.getInt(t, PROBE) == 0)
+ localInit();
if ((r = (int)UNSAFE.getLong(t, SEED)) == 0)
r = 1; // avoid zero
}
Regards, Peter
