编年史：为什么忙碌的尾巴在旋转时会产生垃圾（没有什么可阅读的）？
我有一个忙碌的循环，其中尾巴人不断地试图从队列中阅读：
final Bytes<ByteBuffer> bbb = Bytes.elasticByteBuffer(MAX_SIZE, MAX_SIZE);
// Busy wait loop.
while (true) {
tailer.readDocument(wire -> {
wire.read().marshallable(m -> {
m.read(DATA).bytes(bbb, true);
long rcvAt = m.read(RCVAT).int64();
System.out.println(rcvAt);
});
});
}
为什么即使没有排队没什么可阅读的，为什么此代码会产生垃圾？
相关的JVM标志： ：maxheapsize = 64M
-Server -XX：initialheapsize =
64m -xx
GC日志充满了这样的日志：
...
[30.071s][info][gc ] GC(1755) Pause Young (Normal) (G1 Evacuation Pause) 23M->6M(30M) 0.250ms
[30.084s][info][gc ] GC(1756) Pause Young (Normal) (G1 Evacuation Pause) 23M->7M(30M) 0.386ms
[30.096s][info][gc ] GC(1757) Pause Young (Normal) (G1 Evacuation Pause) 24M->7M(30M) 0.544ms
[30.109s][info][gc ] GC(1758) Pause Young (Normal) (G1 Evacuation Pause) 24M->7M(30M) 0.759ms
[30.122s][info][gc ] GC(1759) Pause Young (Normal) (G1 Evacuation Pause) 24M->7M(30M) 0.808ms
[30.135s][info][gc ] GC(1760) Pause Young (Normal) (G1 Evacuation Pause) 24M->7M(30M) 0.937ms
...
I have a busy-waiting loop in which a tailer is constantly trying to read from a queue:
final Bytes<ByteBuffer> bbb = Bytes.elasticByteBuffer(MAX_SIZE, MAX_SIZE);
// Busy wait loop.
while (true) {
tailer.readDocument(wire -> {
wire.read().marshallable(m -> {
m.read(DATA).bytes(bbb, true);
long rcvAt = m.read(RCVAT).int64();
System.out.println(rcvAt);
});
});
}
Why does this code generate garbage even when there is nothing to read from the queue?
Relevant JVM flags:-server -XX:InitialHeapSize=64m -XX:MaxHeapSize=64m
GC logs and memory profile:
VisualVM
GC logs is flooded with logs like this:
...
[30.071s][info][gc ] GC(1755) Pause Young (Normal) (G1 Evacuation Pause) 23M->6M(30M) 0.250ms
[30.084s][info][gc ] GC(1756) Pause Young (Normal) (G1 Evacuation Pause) 23M->7M(30M) 0.386ms
[30.096s][info][gc ] GC(1757) Pause Young (Normal) (G1 Evacuation Pause) 24M->7M(30M) 0.544ms
[30.109s][info][gc ] GC(1758) Pause Young (Normal) (G1 Evacuation Pause) 24M->7M(30M) 0.759ms
[30.122s][info][gc ] GC(1759) Pause Young (Normal) (G1 Evacuation Pause) 24M->7M(30M) 0.808ms
[30.135s][info][gc ] GC(1760) Pause Young (Normal) (G1 Evacuation Pause) 24M->7M(30M) 0.937ms
...
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您已经捕获了Lambda。他们对BBB有一个引用，因此在每个中间的关系中都会创建。
您可以将它们存储在循环外部的本地变量中，以避免每次创建它们。
我建议使用飞行记录器，因为它使用的垃圾较少来监视应用程序
You have capturing lambda. They hold a reference to the bbb and thus get created on every interation.
You can store them in local variables outside the loop to avoid them being created each time.
I suggest using Flight Recorder as it uses far less garbage to monitor the application