We have a process that is executed as a windows service,
This process serves as an interface server processing incoming messages, transforms them and sends them out to another interface.
it is a rather heavy process, it needs to load a lot of things into memory and that takes some time (few minutes).
due to its nature, when we start it using its windows service, it remains in "starting" status for a very long time (sometimes more than 20 minutes)
even when we can see the process already works and process messages just fine (going by its logs).
so the question is - when is a service considered "starting" and when is it considered "started"? based on what factors?
Starting status finish when onstart is completed.
You should write starting code after onstart event.
puclic class Service1
{
private Timer timer = new Timer();
protected override void OnStart(string[] args)
{
this.timer.Elapsed += new ElapsedEventHandler(OnElapsedTime);
this.timer.Interval = 1 * 1000; // 1 second
this.timer.Enabled = true;
}
private void OnElapsedTime(object source, ElapsedEventArgs e)
{
this.timer.Enabled = false; // OnElapsedTime run only one time
// Write your code
}
}
Related
This question is about running a non-blocking, high-performance activity in nativescript that is needed for the simple task of reading and saving raw audio from the microphone by directly accessing the hardware through the native Android API. I believe I have brought the nativescript framework to the edge of its capabilities, and I need experts' help.
I'm building a WAV audio recorder in Nativescript Android. Native implementation is described here (relevant code below).
In short, this can be done by reading audio steam from an android.media.AudioRecord buffer, and then writing the buffer to a file in a separate thread, as described:
Native Android implementation
startRecording() is triggered by a button press, and starts a new Thread that runs writeAudioDataToFile():
private void startRecording() {
// ... init Recorder
recorder.startRecording();
isRecording = true;
recordingThread = new Thread(new Runnable() {
#Override
public void run() {
writeAudioDataToFile();
}
}, "AudioRecorder Thread");
recordingThread.start();
}
Recording is stopped by setting isRecording to false (stopRecording() is triggered by a button press):
private void stopRecording() {
isRecording = false;
recorder.stop();
recorder.release();
recordingThread = null;
}
Reading and saving buffer is stopped if isRecording = false:
private void writeAudioDataToFile() {
// ... init file and buffer
ByteArrayOutputStream recData = new ByteArrayOutputStream();
DataOutputStream dos = new DataOutputStream(recData);
int read = 0;
while(isRecording) {
read = recorder.read(data, 0, bufferSize);
for(int i = 0; i < bufferReadResult; i++) {
dos.writeShort(buffer[i]);
}
}
}
My Nativescript javascript implementation:
I wrote a nativescript typescript code that does the same as the native Android code above. The problem #1 I faced was that I can't run while(isRecording) because the javascript thread would be busy running inside the while loop, and would never be able to catch button clicks to run stopRecording().
I tried to solve problem #1 by using setInterval for asynchronous execution, like this:
startRecording() is triggered by a button press, and sets a time interval of 10ms that executes writeAudioDataToFile():
startRecording() {
this.audioRecord.startRecording();
this.audioBufferSavingTimer = setInterval(() => this.writeAudioDataToFile(), 10);
}
writeAudioDataToFile() callbacks are queued up every 10ms:
writeAudioDataToFile() {
let bufferReadResult = this.audioRecord.read(
this.buffer,
0,
this.minBufferSize / 4
);
for (let i = 0; i < bufferReadResult; i++) {
dos.writeShort(buffer[i]);
}
}
Recording is stopped by clearing the time interval (stopRecording() is triggered by button press):
stopRecording() {
clearInterval(this.audioBufferSavingTimer);
this.audioRecord.stop();
this.audioRecord.release();
}
Problem #2: While this works well, in many cases it makes the UI freeze for 1-10 seconds (for example after clicking a button to stop recording).
I tried to change the time interval that executes writeAudioDataToFile() from 10ms to 0ms and up to 1000ms (while having a very big buffer), but then the UI freezes were longer and, and I experienced loss in the saved data (buffered data that was not saved to the file).
I tried to offload this operation to a separate Thread by using a nativescript worker thread as described here, where startRecording() and stopRecording() are called by messages sent to the thread like this:
global.onmessage = function(msg) {
if (msg.data === 'startRecording') {
startRecording();
} else if (msg.data === 'stopRecording') {
stopRecording();
}
}
This solved the UI problem, but created problem #3: The recorder stop was not executed on time (i.e. recording stops 10 to 50 seconds after the 'stopRecording' msg.data is received by the worker thread). I tried to use different time intervals in the setInterval inside the worker thread (0ms to 1000ms) but that didn't solve the problem and even made stopRecording() be executed with greater delays.
Does anyone have an idea of how to perform such a non-blocking high-performance recording activity in nativescript/javascript?
Is there a better approach to solve problem #1 (javascript asynchronous execution) that I described above?
Thanks
I would keep the complete Java implementation in actual Java, you can do this by creating a java file in your plugin folder:
platforms/android/java, so maybe something like:
platforms/android/java/org/nativescript/AudioRecord.java
In there you can do everything threaded, so you won't be troubled by the UI being blocked. You can call the Java methods directly from NativeScript for starting and stopping the recording. When you build your project, the Java file will automatically be compiled and included.
You can generate typings from your Java class by grabbing classes.jar from the generated .aar file of your plugin ({plugin_name}.aar) and generate type declarations for it: https://docs.nativescript.org/core-concepts/android-runtime/metadata/generating-typescript-declarations
This way you have all the method/class/type information available in your editor.
We have our application hosted on Azure Cloud Service containing a Web Role and a Worker Role. The worker role is used for running workflows using Windows Workflow Foundation and other processing works.
We are facing an issue where on encountering a Task.Delay, the thread stops responding in the Worker Role. Initially we were using the Task.Delay in a Custom Code Activity inside Workflow Foundation and on encountering the Task.Delay, the subsequent activities in the workflow would never get triggered. We tried to modify the logic by using a delay activity but faced the same issue.
Recently we changed the logic where are executing a method from the activity (in a fire-and-forget fashion) and calling Task.Delay in that method. But even in this mechanism we are still facing the same problem where the thread stops responding as soon as it hits Task.Delay.
public class CommandStatusCheckerActivity : BaseCodeActivity<Job> //Last Activity in the Workflow
{
protected override Job Execute(CodeActivityContext context)
{
var job = JobContext.Get(context);
var statusUpdater = new JobStatusUpdaterAsync();
//Fire and Forget
Task.Run(
() => statusUpdater.Update(job));
return job;
}
}
public class JobStatusUpdaterAsync
{
public JobStatusUpdaterAsync()
{
//Initialization
}
public void Update(Job job)
{
var iteration = 1;
do
{
_tableLogger.LogMessage(“Sleep Started”);
Task.Delay(backoffDelay).Wait();
_tableLogger.LogMessage(“Active Again”); //This Line is never executed
//Actual Polling Logic
iteration++;
} while (ellapsedTime < timeout && inprogressItems.Any());
}
}
I would like to call out that at the same time there are multiple operations which are happening in the worker role and all those threads are getting completed successfully. But none of the other threads have a Task.Delay in them.
Surprisingly we cannot reproduce the same situation in Local machine, it's happening only in our Cloud Service Worker Role.
Out Worker Role Size in Standard_D2.
Any guidance would be appreciated.
I am using JNA to access User32 functions (I dont think it has got to do with Java here, more of concept problem). In my application, I have a Java process which communicates with the Canon SDK. To dispatch any messages I am using the below function:
private void peekMessage(WinUser.MSG msg) throws InterruptedException {
int hasMessage = lib.GetMessage(msg, null, 0, 0);
if (hasMessage != 0) {
lib.TranslateMessage(msg);
lib.DispatchMessage(msg);
}
Thread.sleep(1);
}
peekMessage is called in a loop and it all works well. Whenever an Image is taken from camera, I get the event and do the rest.
But I have observed, say after about 15 seconds (sometimes never or sometimes just at start) of no activity with camera, taking picture does not give me any download event. Later the whole application becomes unusable as it doesn't get any events from camera.
What can be the reason for this? Please let me know of any other info needed, I can paste the respective code along.
Edit:
Initialization:
Map<String, Integer> options = new HashMap<String, Integer>();
lib = User32.INSTANCE;
hMod = Kernel32.INSTANCE.GetModuleHandle("");
options.put(Library.OPTION_CALLING_CONVENTION, StdCallLibrary.STDCALL_CONVENTION);
this.EDSDK = (EdSdkLibrary) Native.loadLibrary("EDSDK/dll/EDSDK.dll", EdSdkLibrary.class, options);
private void runNow() throws InterruptedException {
while (!Thread.currentThread().isInterrupted()) {
Task task = queue.poll();
if (task != null) {
int taskResult = task.call();
switch (taskResult) {
case (Task.INITIALIZE_STATE):
break;
case (Task.PROCESS_STATE):
break;
case (Task.TERMINATE_STATE): {
//queue.add(new InitializeTask());
Thread.currentThread().interrupt();
break;
}
default:
;
}
}
getOSEvents();
}
}
WinUser.MSG msg = new WinUser.MSG();
private void getOSEvents() throws InterruptedException {
if (isMac) {
receiveEvents();
} else {
peekMessage(msg);
}
}
Above, whenever I get my camera event, it add's it to the queue and in each loop I check the queue to process any Task. One more important information: This is a process running on cmd and has no window. I just need the events from my camera and nothing else.
The code where I register callback functions:
/**
* Adds handlers.
*/
private void addHandlers() {
EdSdkLibrary.EdsVoid context = new EdSdkLibrary.EdsVoid(new Pointer(0));
int result = EDSDK.EdsSetObjectEventHandler(edsCamera, new NativeLong(EdSdkLibrary.kEdsObjectEvent_All), new ObjectEventHandler(), context).intValue();
//above ObjectEventHandler contains a function "apply" which is set as callback function
context = new EdSdkLibrary.EdsVoid(new Pointer(0));
result = EDSDK.EdsSetCameraStateEventHandler(edsCamera, new NativeLong(EdSdkLibrary.kEdsStateEvent_All), new StateEventHandler(), context).intValue();
//above StateEventHandler contains a function "apply" which is set as callback function
context = new EdSdkLibrary.EdsVoid(new Pointer(0));
result = EDSDK.EdsSetPropertyEventHandler(edsCamera, new NativeLong(EdSdkLibrary.kEdsStateEvent_All), new PropertyEventHandler(), context).intValue();
//above PropertyEventHandler contains a function "apply" which is set as callback function
}
You are getting ALL messages from ALL windows that belong to this thread, that includes all mouse moves, paints etc. if you aren't rapidly calling this function your message queue will overflow and cause the behavior you describe.
The sleep you definitely don't want as GetMessage yields if no message is waiting.
So if there exists a normal message pump(s) (i.e GetMessage/DispatchMessage) loop somewhere else for this threads window(s) then you should let that pump do most of the work, perhaps use wMsgFilterMin, wMsgFilterMax to just get the event message you require; or even better in this case use peekmessage with PM_NOREMOVE (then you will need your sleep
call as peekmessage returns immediately).
Alternatively provide the hWnd of the window that generates the event to reduce the workload.
Use spy++ to look into which windows this thread owns and what messages are being produced.
To take this answer further please provide answers to: what else is this thread doing and what windows does it own; also is this message pump the only one or do you call into the SDK API where it may be pumping messages too?
There is an OpenSource project wrapping EDSDK with JNA and it has a version of your code that is probably working better:
https://github.com/kritzikratzi/edsdk4j/blob/master/src/edsdk/api/CanonCamera.java#L436
Unfortunately this is not platform independent and specifically the way things work on windows. I am currently in the process of trying to get a MacOS version of things working at:
https://github.com/WolfgangFahl/edsdk4j
I developed Windows service that is using System.Threading.Timer. Timer is starting every x minutes and it works fine (timer is updatet at the end of method). But, if there is an error in try block service just stops despite the fact that I'm updating timer and telling him when to start again
why is that happening? Here is code :
System.Threading.Timer serviceTimer;
protected override void OnStart(string[] args)
{
TimeSpan diff;
diff = nextRun - now;
TimerCallback timerDelegate =
new TimerCallback(MyTimerCallback);
serviceTimer = new System.Threading.Timer(timerDelegate, null,
diff, new TimeSpan(-1));
}
public void MyTimerCallback(object something)
{
try
{
//possible error that happened
}
catch(Exception)
{
}
finally
{
//diff is a new variable telling timer when to start again
serviceTimer.Change(diff, new TimeSpan(-1));
}
}
what am I missing why service stops if there was an error?
Maybe the timer wasn't able to change. Timer.Change returns a boolean:
true if the timer was successfully updated; otherwise, false.
But you're not checking that result. I'd recommend probably disposing the timer and newing up a new one each time, since it's already fired and you created it as a "one shot" timer, e.g.
finally
{
serviceTimer.Dispose();
serviceTimer = new System.Threading.Timer(timerDelegate, null,
diff, new TimeSpan(-1));
}
In case that someone deals with same problem I figured something like this:
Since I want my service to stay alive no matter what :
I 'm reporting to the service manager that the service has successfully started -
base.OnStart(args);
In configuration you can set legacyUnhandledExceptionPolicy set to true (1)
I am trying to make a simple server thread in QT to accept a connection, however although the server is listening (I can connect with my test app) I can't get the newConnection() signal to be acted on.
Any help as to what I'm missing here would be much appreciated!
class CServerThread : public QThread
{
Q_OBJECT
protected:
void run();
private:
QTcpServer* server;
public slots:
void AcceptConnection();
};
void CServerThread::run()
{
server = new QTcpServer;
QObject::connect(server, SIGNAL(newConnection()), this, SLOT(AcceptConnection()));
server->listen(QHostAddress::Any, 1000); // Any port in a storm
exec(); // Start event loop
}
void CServerThread::AcceptConnection()
{
OutputDebugStringA("\n***** INCOMING CONNECTION"); // This is never called!
}
First of all I can say that your server lives in new thread while CServerThread instance lives in another thread (in the thread this instance was created). Signal/slot connection you are creating is inderect and uses thread save event delivery between events loops of two different threads. It actually can cause such problem if thread where you creating CServerThread doesn't have Qt event loop running.
I suggest you to create some MyServer class which creates QTcpServer and calls listen and connects QTcpServer::newConnection() signal to its own slot. Then rewrite your server thread run method to something like this:
void CServerThread::run() {
server = new MyServer(host,port);
exec(); // Start event loop
}
In this approach both QTcpServer and newConnection processing object lives in the same thread. Such situation is easier to handle.
I have one really simple working example:
Header: http://qremotesignal.googlecode.com/svn/tags/1.0.0/doc/html/hello_2server_2server_8h-example.html
Source: http://qremotesignal.googlecode.com/svn/tags/1.0.0/doc/html/hello_2server_2server_8cpp-example.html