Colleagues,
Can you please advise me a bit about the following.
I cannot figure out how to pass value through process variable from main flow to its subflow in Camunda. I am putting value to process variable in one task in main flow via execution.setVariable("toolId", toolId);
where execution is an instance of DelegateExecution. I am trying to retrieve in another task of subflow via
Long toolId = (Long) execution.getVariable("toolId");
However I am getting null.
By subflow I assume you mean a call activity (otherwise the data would be available).
A call activity references a technically independent process instance with its own data. Therefore you have to explicitly map the in data, which should be copied from the source (parent) to the target (sub process) and also the out data in the other direction.
Please see: https://docs.camunda.io/docs/components/modeler/bpmn/call-activities/#variable-mappings and https://docs.camunda.io/docs/components/concepts/variables/#inputoutput-variable-mappings
Related
Im running a workflow using a step function (with SAM), when I needed to send information between lambdas I've used events and everything was perfect! But now, I need that almost every lambda in my workflow have access to a constant received in the invocation input of the step function (it changes on every execution) like a global variable.
I know that I can solve it by returning it in every lambda output but I think that it is a very ugly solution :(
Is there any way to access the context of the execution and add data to it from a lambda in the step function ? Any other solution would be cool too.
Yes, see https://docs.aws.amazon.com/step-functions/latest/dg/input-output-resultpath.html#input-output-resultpath-append
You can keep the input of the state machine execution and combine it with the result of the state.
Going through the docs, I see that you can access the context object from each state in the state machine.
You can pass the information that you need to be global as the input to your state machine and then, access the state machine input from the context object.
You can refer the linked doc to see how to access the context object.
I am trying to get around the old "How do I get a Windows Performance Counter for the current process" issue. Basically I am enumerating Process Object instances to get a list of Process objects that I can then query for their process id and compare to my own.
Based on this I can build a performance counter path using the correct instance index (to create something similar to \Process(my_program#3)\<counter>) that I can then use to query whatever counter it is that I am interested in. But what happens if one or more of the other instances of my_program exit prior to the PdhAddCounter call? If I understand correctly, this would mean that my counter path now refers to a different process or is now invalid. They might even disappear while querying for the process id...
How do I prevent the counter path from becoming invalid before I can use it to get a counter handle?
Wow, you are right. This seems like a major design flaw to me. Basically it is impossible to reliably monitor an instance if it's name is not unique. I did stumble across a workaround specifically for the Process and Thread objects, but that's a global setting that could affect other applications.
I think the safest way to do this would be to watch all process objects, and each time you collect the data go through and find the one with the desired Process Id.
In the context of Windows Job Objects, how can I get the job object for the current process (in case it is in a job object)? The IsProcessInJob function lets me test whether a given process (e.g. the current one) is in a given (or any) job - but it doesn't yield the handle of the matching job.
If you just want to find out what quotas/limits you are running under, or enumerate all the other processes in the job, you don't need to get the Job object for the current process.
You can call QueryInformationJobObject with NULL, which will be the Job object of the current process.
QueryInformationJobObject: http://msdn.microsoft.com/en-us/library/ms684925(VS.85).aspx
Job Objects: http://msdn.microsoft.com/en-us/library/ms684161(VS.85).aspx
Set job attributes using SetInformationJobObject
To answer the specific question, call IsProcessInJob find out if you are in a job.
You can find out everything about the Job by passing NULL to QueryInformationJobObject
Your child processes will inherit your job automatically, unless you pass CREATE_BREAKAWAY_FROM_JOB and the job has JOB_OBJECT_LIMIT_BREAKAWAY_OK or JOB_OBJECT_LIMIT_SILENT_BREAKAWAY_OK is set. In these cases you can assign the process to a new job if you wish.
So without knowing the handle, you can find out all about your current Job, and assign child processes within the current job, or if you have permission, without the current job. I.e. you can do almost everything the handle would allow you to do.
The only exception is duplicate it to another sibling process. If you need to do that you will have to have the parent process communicate the handle value to you somehow.
I'm somehow stuck with implementing a reporting functionailty in my Log-Parser Application.
This is what I did so far:
I'm writing an Application that reads Logfiles and searches the strings for multiple regular Expressions that can be defined in a user-configuration file. For every so called "StringPipe"-defintion that is parsed from the configuration the Main-Process spawns a worker thread that will search for a single regex. The more definitons the user creates, the more worker threads are spawned. The Main Function reads a bunch of Logstrings and then sends the workers to process the strings and so on.
Now I want every single worker thread that is spawned to report information about the number of matches it has found, how long it took, what it did with those strings and so on. These Information are used to export as csv, write to DB and so on.
Now I'm stuck at the point where I created a Class "Report". This Class provides member functions that are called by the worker threads to make the Report-Class gather the Infos needed for generating the report.
For that my workers (which are boost::threads / functors) have to create a Report-Object which they can call those reporting functions for.
The problem is in my Design, because when a worker-thread finishes his job, it is destroyed and for the next bunch of strings that needs to be processed a new instance of this worker functor is spawned and so it needs to create a new Report Object.
This is a problem from my understanding, because I need some kind of container where every worker can store it's reported infos into and finally a global report that contains such infos as how long the whole processing has taken, which worker was slowest and so on.
I just need to collect all these infos together, but how can I do this? Everytime a worker stops, reports, and then starts again, it will destroy the Report-Object and it's members, so all the infos from previous work is gone.
How can I solve this problem or how is such a thing handled in general?
First, I would not spawn a new thread do the RE searching and such. Rather, you almost certainly want a pool of threads to handle the jobs as they arise.
As far as retrieving and processing the results go, it sounds like what you want are Futures. The basic idea is that you create an object to hold the result of the computation, and a Future to keep track of when the computation is complete. You can either wait for the results to be complete, or register a call-back to be called when a future is complete.
Instead of having the worker thread create the report object, why don't you have the main thread create the empty report and pass a pointer to the worker thread when created. Then the worker thread can report back when it has completed the report, then the main thread can add the data from that report to some main report.
So, the worker thread will never have ownership of the actual report, it fill just populate its data fields and report back to the main thread.
I have a program which needs to invoke a process to perform an operation and wait for it to complete the operation. The problem is that the invoked process clones itself and exits, which causes the wait api to return when the process exits. How can I wait for the cloned process to finish execution and return?
I am using the windows JOB object as mentioned in http://www.microsoft.com/msj/0399/jobkernelobj/jobkernelobj.aspx, But I am not sure if this is the best way.
umm, I'm pretty sure you can can the spawner process id from any process. I'd iterate through all the processes, find the one's who's parent id matches the one of the process you spawned, and wait for it to die.
alternatively (I mean, thats pretty hack) what is the child child process doing? is there some other way you could detect when it has finished doing what it is meant to do?
a hack way to get a process's parent id
http://www.codeguru.com/cpp/w-p/win32/article.php/c1437
takes a handle, and using the method in the code above, returns the parent id.
http://msdn.microsoft.com/en-us/library/ms684280(VS.85).aspx
OpenProcess takes an id, gets a handle to it (if you're lucky)
http://msdn.microsoft.com/en-us/library/ms684320(VS.85).aspx
GetProcessId takes a handle, gets it's id.
http://msdn.microsoft.com/en-us/library/ms683215(VS.85).aspx
GetExitCodeProcess takes a handle, returns whether the process is done or not.
http://msdn.microsoft.com/en-us/library/ms683189(VS.85).aspx
so appart from using hidden nt calls that it expressly tells you not to, you would basically have to create your process, get it's id, then spam all the process, opening them and checking their parent ids against the id of the process you created, if you didn't find one, then it's done, if you do, spam it with GetExitCodeProcess until its done.
I haven't tested any of this, but it looks like A way to do it. though if it's THE BEST way to do it I might just have to loose all faith in windows...
+1 for using job objects ;)
Assuming the process that you're running isn't spawning the cloned version of itself in such a way that it breaks out of the job...
You should be able to simply monitor the job events and act on JOB_OBJECT_MSG_ACTIVE_PROCESS_ZERO (see JOBOBJECT_ASSOCIATE_COMPLETION_PORT and SetInformationJobObject()). Monitoring the job in this way will also give you notifications of the processId's of new processes created within the job and details of when they exit.
If you have control over the source of invoked process, one possible solution would be to make it wait for the process it spawns by cloning itself.