I have exactly one Node server, which is currently running some code. This code is now outdated. How can I switch to the new code without any server down-time? Do I need to get another server to act as a buffer?
Basically you "kill" the old process and immediately start the server again, read the following article for more details & code sample:
http://codegremlins.com/28/Graceful-restart-without-downtime
Related
I implemented an UWP Server Socket following the sample here and it correctly works.
Now I want to make the app able to continuously accept requests, but I expect that when the app is suspendeded and a client sends a request, the server is not able to respond. If I am correct, what is the best way to avoid this status change? If possible, I would prefer a solution with Extended Execution instead of implementing a Background Task, but I don't know if the following code in the OnSuspending method is enough to keep the app in the Running status:
var newSession = new ExtendedExecutionSession();
newSession.Reason = ExtendedExecutionReason.Unspecified;
newSession.Revoked += SessionRevoked;
I saw people calling a "LongRunningWork()" function in other samples, but in my case the code to execute is already defined in the code-behind of the view as shown in the link above, so I would like simply keeping the app always running. Keep in mind that it is a LOB application, so I don't have Store limits.
I have a kind of proxy server running on a WebServer module and I noticed that this server is being killed due to its memory consumption.
Every time the server gets a new request it creates a child client process, the problem I see is that the process remains alive indefinitely.
Here is the server I'm using:
server.js
I thought response.close() was closing and killing client connections, but it is not.
Here is the list of child processes displayed on htop:
(Those process are even more, it is just a fragment of the list)
I really need to kill those processes because they are using all the free memory. Am I missing something?
I could simply restart the server, but the memory will still be wasted.
Thanks you !
EDIT:
The processes I mentioned before are threads and no independient processes as I thought (check this).
Every http request creates a new thread, and that's ok, but this thread is not being killed after the script ends.
Also, I found out that no new threads are created if the request handler doesn't run casper (I mean casper.run(..)).
So, new threads are created only if the server runs a casper instance, the problem is that this instance doesn't end after run function does.
I tried casper.done() as mentioned below, but it kill the whole process instead of the current running thread. (I did not find any doc for this function).
When I execute other casper scripts, outside the server in the same machine, the instanced threads and the whole phantom process ends successfully. What would be happening?
I am using Phantom 2.1.1 and Casper 1.1.1 versions.
Please ask me anything if you want more or specific information.
Thanks again for reading !
This is a well known issue with casper:
https://github.com/casperjs/casperjs/issues/1355
It has not been fixed by the casper guys and is currently marked as an enhancement. I guess it's not on their priority list.
Anyways, the workaround is to write a server side component e.g. a node.js server to handle the incoming requests and for every request run a casper script to do the scraping in a new child process. This child process will be closed when casper terminates it's job. While this is a workaround, it is not an optimal solution as the cost of opening a child process for every request is not cheap. it will be hard to heavily scale an approach similar to this. However, it is a sufficient workaround. More on this fully sensible approach is in the link above.
I have an ASP.NET application that is using Entity Framework 6 to access data stored in an Azure SQL database. I've run into a bit of a problem connecting to the database as a whole.
If I spawn a new database instance on Azure, start my app in the debugger and step through it, I'll see that it connects without a problem, can access the seed data and all is well (inserts work without a problem, but this occurs whether I change the data or not).
However, if I restart the debugger and at all points after that attempt to connect to the database when my app restarts, the connection will fail. If I set a breakpoint and look at the Context value in the Locals window, I have the following error as the value for all DbSets:
Function evaluation disabled because a previous function evaluation
timed out. You must continue execution to reenable function
evaluation.
Despite having a try/catch around the logic, no exception will be thrown. If I step into/out of/over this, the application will just run indefinitely and never complete.
If I do a rollback to the $InitialDatabase and then re-apply the automatic migration (via update-database), I still cannot connect to the database, however if I delete the database in Azure, spin up a new one, set up the new connection information in the Web.config file and execute all over again, it'll work like a charm one time. After that, it'll fail to work again, despite no other changes to the application.
What's going on here and why is this behavior occurring? If there's an underlying problem here, how could I tell what it is and how can I resolve it?
Thanks!
After making no headway, I rolled-back to a previous version of my code from when it was working fine about three weeks back. I've updated all the logic to match what was in the latest build, I just haven't updated any of the assemblies yet. It's working perfectly fine and connecting every time now, so apparently this is the fault of one of the as-of-yet unidentified dependencies.
If I ever determine which one, I'll update this answer accordingly.
I have two very basic questions on WebSphere MQ - given that I had been kind of administrating it for past few months I tend to think that these are silly questions
Is there a way to "deactivate" a
queue ? (for example through a
runmqsc command or through the
explorer interface) - I think not. I
think what I can do is just delete
it.
What will happen if I create a
remote queue definition if the real
remote queue is not in place? Will
it cause any issues on the queue
manager? - I think not. I think all
I will have are error messages in
the logs.
Please let me know your thoughts.
Thanks!
1 Is there a way to "deactivate" a
queue?
Yes. You can change the queue attributes like so:
ALTER Q(QUEUE_NAME) PUT(DISABLED) GET(DISABLED)
Any connected applications will receive a return code on the next API call telling them that the queue is no longer available for PUT/GET. If these are well-behaved programs they will then report the error and either end or go into a retry loop.
2 What will happen if I create a
remote queue definition if the real
remote queue is not in place?
The QRemote definition will resolve to a transmit queue. If the message can successfully be placed there your application will receive a return code of zero. (Any unsuccessful PUT will be due to hitting MAXDEPTH or other local problem not connected to the fact that the remote definition does not exist.)
The problem will be visible when the channel tries to deliver the message. If the remote QMgr has a Dead Letter Queue, the message will go there. If not, it will be backed out onto the local XMitQ and the channel will stop.
I have a small GWT application that gets the contents for a FlexTable from a database based on some string parameters. It is triggered by the click of a button on the GUI.
Everything works as expected when the app is initially started. But, upon multiple clicks (requests), the app stops working and my requests from the client no longer reaches the sever code. I am running on hosted mode and have breakpoints in my code. I can trace the code on client side; but after it submits the request to server using my service instance, it never reaches the server; nor the onSuccess() gets called.
Can someone please help me debug this? Where should i start to see traces of what is happening?
Turns out that it wasnt anything about GWT RPC. The request was indeed getting submitted to server but because of a db resource contention, Eclipse wasn't showing me any trace of the code on server side. I switched on debug loggings in the code and everything because real clear.
Thanks!
pjames