I currently have a WorkerRole doing that for me.
Basically, it keeps sleeping and wakes up every hour to call the service.
But with the recent release (in my country) of Azure Scheduler, I'm wondering if I can replace that non-free WorkerRole with a free Sheduler job.
So I tried creating a job with a PUT request like this one:
http://.azurewebsites.net/ClientBin/.svc/binary/
But I get the following error in the scheduler history:
502 - Web server received an invalid response while acting as a
gateway or proxy server.
Is it a URL problem?
Is it an authentication issue?
Is it even feasible?
Thanks!
I eventually used a WebJob to do my recurring task.
Related
I have been struggling with a problem in Google App Engine, using Java, for several days.
Many times (about 50% of the time) when I try to request the connection to a Cloud Sql instance, the connection returns a null value, resulting in several NullPointerException messages when trying to invoke Cloud Sql queries (when invoking .prepareCall(stored_proc)).
I have the latest App Engine Java SDK, in a project service, shared with other services built in Python which consume this Java backend.
Could it be possible that after certain time the instance/s could crash (I am just testing at this point, so I am using default scalation)?
This is the code that returns null:
Class.forName("com.mysql.jdbc.GoogleDriver");
url = "jdbc:google:mysql://project:instance/database?user=root";
log.info(url);
return DriverManager.getConnection(url);
This is part of my configuration file:
<application>app</application>
<module>mod</module>
<version>1</version>
<threadsafe>true</threadsafe>
<use-google-connector-j>true</use-google-connector-j>
I tried several suggestions from other posts, but with no success at all.
Any suggestion will be welcome, thanks in advance.
I was facing the same problem while using Google Cloud SQL and App engine.
I solved the problem by managing the connection pool my self. I realised that when you request a new connection for each request and close it on completion of the thread. The other requests would get back a null resulting to NullPointException.
I decided to do the following and it work for me for like 2 years now.
Open a connection and keep it to a static class that has a number of connections;
Every time i want to find a connection to the database, i would first check if the is an available connection for me to use.
Incase a Query killed the connection, thus means i needed to request another extra connection just to for the sack of connection drops.
I will add this as an answer, since it is not exactly what Chrispinus mentioned, although he gave me a good idea for teh solution.
I went deeper in the code and found that some of the methods were not closing the database connection. I had assumed all of them were doing that, but looking at each method, I found I was wrong.
So, although it sounds obvious, check connections are being closed (or managed, as Chrispinus says) properly.
When running my PHPUnit tests, I get the following error
PDOException: SQLSTATE[08004] [1040] Too many connections
I am running a lot of tests, but I am afraid this could happen in a not-test situation as well.
My tests are doing guzzle requests to my Lumen 5.2 API. The Lumen API basically gets a request and checks the oAuth token (connecting to the oAuth DB). If it is correct it connects to a different database (this is done by setting the $connection variable in the Model) and uses the Model to retrieve data.
Is the model not closing the connection?
Any idea? Is there any information I should provide, to help solve this problem?
I think it was actually due to PHPUnit being one huge script. Apparently Laravel/Lumen disconnects when the script finishes, but all testscases seem to count as one script. Adding \DB::disconnect(); in the tearDown solved my issue.
I planning to create a NodeJS program, that work 24/7, that ping and make requests to an external server (outside of google cloud) every minute. Just to see that it the external services are are live.
If there is any error it will notify me by SMS & Email.
I don't need any front-end for this app, and no one needs to connect to it. Just simple NodeJS program.
The monitoring and configuration will be by texts files.
Now the questions:
It looks like it will cost me just $1.64. It sounds very cheap. Am I missing something?
It needs to work around the clock, I will request it to start it once, and it need to continue working, (by using setInterval). Is it will be aborted?
What it is exactly mean buy 1 instance. What an instance can do? Only respond to one request or what?
I tried to search in Google: appengine timeout, but didn't found anything that helps.
Free Quota
If you write your application in Python, PHP, Go or Java it can fit in free usage quota:
https://cloud.google.com/appengine/docs/quotas
So there will be absolutely no costs to run it on Google App Engine platform.
There are limit of 657,000 UrlFetch API Calls per day (more than 450 calls per minute in 24/7 mode) for free apps. 4GB traffic may also be sufficient for this kind of work.
Keep in mind there is no SMS sending services provided by Google App Engine and you will need to spend additional UrlFetch API calls to use external SMS services.
Email sending is also limited to 100 Emails per day (or 5000 Emails to admin address), so try not so send repeated notifications about same monitored server every minute, or you'll deplete your Email quote in 1.5 hours.
Scheduled Tasks
There is no way to run single process indefinitely without interruption on App Engine. But you don't have to!
You'll need to encapsulate all the work you're planning to execute in every iteration into single task and then schedule it to run every minute with Cron. See this documentation for Python: https://cloud.google.com/appengine/docs/python/config/cron
It is recommended to have some configuration page where you can set some internal configuration or see monitoring statistics, at least manage flag to temporarily pause tasks execution without redeploying your app.
I am unable to update my frontends nor my backends. I get the error message 'Version is not ready'. This bug has persisted for coming up to 24 hours now. I have a task perpetually running in a queue. My best guess is that this task is stopping the update. I am unable to delete the task as it is perpetually running, nor can I delete the queue as I am unable to upload a new queue.yaml definition. The same task previously failed due to a maximum recursion error as I had a synchronous RPC within an asynchronous tasklet.
I'm pretty sure the fix will require someone from the GAE side forcibly resetting the task queue. Thus, this question would be more suitably directed to the GAE team with details about my app in a less public forum. Though, from what I can see, they do not allow direct support questions and suggest posting the question here. My follow up question, then, is when you have a GAE issue that requires action from the GAE team - how do you get hold of them (other than paying US$500/month for a premium support account)?
EDIT:
The task is/was meant to be running on a backend instance. I intended to shutdown all backend and frontend instances via the console assuming that they would cancel the task and restart themselves. But I found that only one frontend instance was running - no backends. After shutting down that frontend instance, the dashboard has reported that I have 0 instances running, yet the website is still serving and the task remains perpetually running.
EDIT:
Disabling the app stopped the task from running. After reenabling the app, I was able to update it. Though I am left with a ghost task in my queue.
If you have a stuck task queue job, I'd try disabling the queue and killing the instance running that job. If that doesn't work, I'd try disabling the app temporarily.
We have been using push queue for a very long time and have no problems in consuming the tasks from a dev server.
However during implementing a new service with pull queue, it became difficult to figure out how to do the same thing on the dev server.
Basically from the docs, what we can see is that you should use a REST api (we can't use the direct queue api as it is consumed by an external app) to lease/delete a task with the end point of
https://www.googleapis.com/taskqueue/v1beta1/projects/taskqueues
But obviously this will not work in local dev server, and it appears that no place have talking about this.
Just wondering if anyone had ever run into the same issue had can shed some light?
With Pull Queue, task consumer can be internal or external.
If you need it to work on dev server, then just create a handler (a servlet) and use internal API to add, lease and delete tasks.