Samza的ApplicationMaster

AMRMClientAsync handles communication with the ResourceManager and provides asynchronous updates on events such as container allocations and completions. It contains a thread that sends periodic heartbeats to the ResourceManager. It should be used by implementing a CallbackHandler:

class MyCallbackHandler implements AMRMClientAsync.CallbackHandler {public void onContainersAllocated(List containers) {[run tasks on the containers]}public void onContainersCompleted(List statuses) {[update progress, check whether app is done]}public void onNodesUpdated(List updated) {}public void onReboot() {}} The client&＃39;s lifecycle should be managed similarly to the following:

AMRMClientAsync asyncClient &＃61; createAMRMClientAsync(appAttId, 1000, new MyCallbackhandler());asyncClient.init(conf);asyncClient.start();RegisterApplicationMasterResponse response &＃61; asyncClient.registerApplicationMaster(appMasterHostname, appMasterRpcPort,appMasterTrackingUrl);asyncClient.addContainerRequest(containerRequest);[... wait for application to complete]asyncClient.unregisterApplicationMaster(status, appMsg, trackingUrl);asyncClient.stop();

这个类是用来做为一个Client和RM进行通信&＃xff0c;并且注册一个用于回调的对象来处理container 的allocation和completion事件。它启动一个线程&＃xff0c;周期性地发送hearbeat至ResourceManager