diff options
Diffstat (limited to 'luni/src/main/java/java/util/concurrent/Exchanger.java')
| -rw-r--r-- | luni/src/main/java/java/util/concurrent/Exchanger.java | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/luni/src/main/java/java/util/concurrent/Exchanger.java b/luni/src/main/java/java/util/concurrent/Exchanger.java index 3c230be..6069dce 100644 --- a/luni/src/main/java/java/util/concurrent/Exchanger.java +++ b/luni/src/main/java/java/util/concurrent/Exchanger.java @@ -2,7 +2,7 @@ * Written by Doug Lea, Bill Scherer, and Michael Scott with * assistance from members of JCP JSR-166 Expert Group and released to * the public domain, as explained at - * http://creativecommons.org/licenses/publicdomain + * http://creativecommons.org/publicdomain/zero/1.0/ */ package java.util.concurrent; @@ -23,7 +23,7 @@ import java.util.concurrent.locks.LockSupport; * to swap buffers between threads so that the thread filling the * buffer gets a freshly emptied one when it needs it, handing off the * filled one to the thread emptying the buffer. - * <pre>{@code + * <pre> {@code * class FillAndEmpty { * Exchanger<DataBuffer> exchanger = new Exchanger<DataBuffer>(); * DataBuffer initialEmptyBuffer = ... a made-up type @@ -59,8 +59,7 @@ import java.util.concurrent.locks.LockSupport; * new Thread(new FillingLoop()).start(); * new Thread(new EmptyingLoop()).start(); * } - * } - * }</pre> + * }}</pre> * * <p>Memory consistency effects: For each pair of threads that * successfully exchange objects via an {@code Exchanger}, actions @@ -135,8 +134,8 @@ public class Exchanger<V> { * races between two threads or thread pre-emptions occurring * between reading and CASing. Also, very transient peak * contention can be much higher than the average sustainable - * levels. The max limit is decreased on average 50% of the times - * that a non-slot-zero wait elapses without being fulfilled. + * levels. An attempt to decrease the max limit is usually made + * when a non-slot-zero wait elapses without being fulfilled. * Threads experiencing elapsed waits move closer to zero, so * eventually find existing (or future) threads even if the table * has been shrunk due to inactivity. The chosen mechanics and @@ -275,7 +274,9 @@ public class Exchanger<V> { * extra space. */ private static final class Slot extends AtomicReference<Object> { - // Improve likelihood of isolation on <= 64 byte cache lines + // Improve likelihood of isolation on <= 128 byte cache lines. + // We used to target 64 byte cache lines, but some x86s (including + // i7 under some BIOSes) actually use 128 byte cache lines. long q0, q1, q2, q3, q4, q5, q6, q7, q8, q9, qa, qb, qc, qd, qe; } |