parse-server version 2.7.4 (Azure on a Standard_B4ms)
mongoDB-server version 3.4.14 (Azure on a separate Standard_B4ms)
I have an iOS & Android app, with LiveQuery (set on the parse-server's VM) that's being used a lot for chatting, where usually there are ± 50 simultaneous users. The thing is, after a few hours of continuous usage, the server's cloud code responses are getting REALLY slow! Not just from a specific one... all cloud functions!
I'm using screen to run the parse server. So I found that if I restart the parse server (not the vm), the app is getting back to normal.
I also have logs enabled at all times. (just mentioning it in case it could be the issue)
I can't understand why this is happening!
Any ideas?
Related
I have an ASP.NEt Core 3.1 application with Angular 8 frontend. It runs fine when hosted on IIS but as I have moved it onto a new Ubuntu 18 Server with Nginx above Kestrel sometimes the long running background processes stop working (IHostedService). Then the app runs towards accepting new requests so only the background process is stopped.
These processes get files from clients and give immediate responses with a process ids. The clients can query the process state by their id. Everything have been running fine for months now on IIS but the new config must have some limits that kills these processes. I suppose there is some kestrel or nginx option I don't know about and affect processes started by http requests.
What options can I try and where can I get some logs?
I've tried to log everything from .net core but even the most verbose logs are useless here. Nginx logs doesn't contain any info about the stopped process either.
Although the application runs fine hosted on IIS I tried to find catch blocks without any output and added logging into them but still nothing. Are there anything I can add to my application globals to log any exceptions handled or unhandled?
I forgot to say that I use a local Microsoft SQL Server Express both on windows and linux. The linux Sql Server install was done by the official ms docs (as dotnet and nginx config, too). The database is restored from a windows sql server backup. The connection string is the same with multipleresultsets=true. Are there any differences I should aware of?
For anyone getting here in the future: this was caused by a bug in Microsoft.Data.SqlClient, so I had to update it (independently from EF Core 3.1.2) from nuget to the newer 1.1.2 version.
When it stucked I had two threads waiting for each other, both in SqlClient. With Just my code enabled VS debugger stopped at one of my linq queries. The only interesting part was that it never threw any exceptions and there was no deadlock event on the sql server either. It just waited there so all logs were empty.
https://github.com/dotnet/efcore/issues/18480
https://github.com/dotnet/SqlClient/issues/262
My application does client authorization over WebSocket connection using ws#7 but after several minutes suddenly it gets disconnected with the error code 1006.
Interesting thing is it's working on AWS Windows Server instances but not on Azure instances or VMWare VMs. I assume there is some kind of configuration related to WebSockets should be handled before installing Node-based application but the main question is what I have to configure in order to move forward.
1006 error usually happens when there is a timeout. In the library you are using, the ws timeout is 30 seconds: https://github.com/websockets/ws/blob/4f293a8726092c75539287dd07358afaf151a2e5/lib/websocket.js
Check whether you are using a gateway or something in between the VM with a timeout less or equal than the ping interval that ws automatically does from the client.
You can usually can see this automatically generated ping messages in Firefox with the F12 tools in the network tab, these do not show up in Chrome nor in Edge but they happen as well:
I had similar problem with my Windows machine tryng to connect a server using Visual Studio Code. I have reset the routes, and reboot the machine, that solve the issue.
To reset use:
route -f
I have a Windows Azure VM(linux server 14.04) running and am able to access the VM using command line on my mac/windows machines. I'm running a node.js server and a mongodb instance on this Azure VM.
The problem is that this nodejs server on the VM gets disconnected after sometime(timeout sort of thing). Is it possible that the server on the VM runs indefinitely and keeps serving requests?
PS: My VM is running indefinitely and properly, but the nodejs server on the VM itself times out after sometime. Please help!
Thanks.
It is probably just crashing!
A barebone node application does not get monitored by itself.
This might sound a little crazy if you come from other web frameworks / platforms like ASP.NET or PHP where you had IIS or Apache monitoring your application for you, which was kind of nice tbh. In node.js you choose your process manager / monitoring system. From my experience, the most popular and well supported PMs are the ones listed in the Expressjs documentation: http://expressjs.com/advanced/pm.html
As Azure VMs will not sleep or shutdown itself , and also will not stop any servers running on them.
And per your description
the nodejs server on the VM itself times out after sometime
The issue seems the same with what #svenskunganka said.
You can check what occurred the error “sometime”, leveraging PM2 as #Daniel and #svenskunganka suggested.
When you deploy your nodejs project with PM2, it will monitor the application and log errors automatically. You can also monitor your VM metrics (such as CUP Usage,Network in/out) from Azure Portal Monitor panel.
I have been struggling to do the tutorial, https://www.windowsazure.com/en-us/develop/nodejs/tutorials/web-app-with-mongodb/, which basically makes a simple node.js application that has access to a Mongo DB. I keep running into the following issue when launching the program locally with the command Start-AzureEmulator:
"No connection could be made because the target machine actively refused it 127.0.0.1:27017"
I tried various ports and configurations with no success. Oddly enough, when I run mongodb.exe, the database launches without hiccup (this is just through the command line not within the Azure Emulator). I have also tried reinstalling all of the tools multiple times. It seems I am at a loss of what to do next.
Have any of you experienced this problem or have been able to complete this tutorial?
As a side note, do any of you know any cloud providers that allow the use of sockets with node.js? This is one of the main reasons I am trying to use Azure.
I assume you've followed the instructions step by step and haven't modified anything yet?
I note from the screenshot below, that the sample tries to open Mongo at 127.255.0.1:27017, not 127.0.0.1:27017:
I suggest checking your Azure services' URL's in case you're looking for Mongo on the wrong address.
This may be a basic question, but how do I go about effeciently deploying updates to currently running node.js code?
I'm coming from a PHP, JavaScript (client-side) background, where I can just overwrite files when they need updating and the changes are instantly available on the produciton site.
But in node.js I have to overwrite the existing files, then shut-down and the re-launch the application. Should I be worried by potential downtime in this? To me it seems like a more risky approach than the PHP (scripting) way. Unless I have a server cluster, where I can take down one server at a time for updates.
What kind of strategies are available for this?
In my case it's pretty much:
svn up; monit restart node
This Node server is acting as a comet server with long polling clients, so clients just reconnect like they normally would. The first thing the Node server does is grab the current state info from the database, so everything is running smoothly in no time.
I don't think this is really any riskier than doing an svn up to update a bunch of PHP files. If anything it's a little bit safer. When you're updating a big php project, there's a chance (if it's a high traffic site it's basically a 100% chance) that you could be getting requests over the web server while you're still updating. This means that you would be running updated and out-of-date code in the same request. At least with the Node approach, you can update everything and restart the Node server and know that all your code is up to date.
I wouldn't worry too much about downtime, you should be able to keep this so short that chances are no one will notice (kill the process and re-launch it in a bash script or something if you want to keep it to a fraction of a second).
Of more concern however is that many Node applications keep a lot of state information in memory which you're going to lose when you restart it. For example if you were running a chat application it might not remember who users were talking to or what channels/rooms they were in. Dealing with this is more of a design issue though, and very application specific.
If your node.js application 'can't skip a beat' meaning it is under continuous bombardment of incoming requests, you just simply cant afford that downtime of a quick restart (even with nodemon). I think in some cases you simply want a seamless restart of your node.js apps.
To do this I use naught: https://github.com/superjoe30/naught
Zero downtime deployment for your Node.js server using builtin cluster API
Some of the cloud hosting providers Node.js (like NodeJitsu or Windows Azure) keep both versions of your site on disk on separate directories and just redirect the traffic from one version to the new version once the new version has been fully deployed.
This is usually a built-in feature of Platform as a Service (PaaS) providers. However, if you are managing your servers you'll need to build something to allow for traffic to go from one version to the next once the new one has been fully deployed.
An advantage of this approach is that then rollbacks are easy since the previous version remains on the site intact.