Disconnected connection could not be gc, cause memory leak

[wts2accuracy]

executor.scheduleWithFixedDelay(Main::xmppConnect, 0, 1, TimeUnit.SECONDS);

xmppConnect(){
// do connect(),login(),and finally disconnect()
}

I don’t know why those connection instance could not be gc,even I call System.gc() after disconnect().

[Flow]

System.gc() does not provide any guarantees at all, especially not for a full GC run. That said, my experience with memory leaks in Java tells me that it is not unlikely that those instances are still uncollected because they a still strongly referenced. But I see that you have the right tool in your hand to find that out.