I have a page which can take long time to process. But in the mean time if the same page is accessed (from the same system), the second instance gets blocked till the first page finishes. Actually instead of the blocking behaviour, I would be happy it the second instance fails rather than getting hung. Is there a way to around to make the same file accessbile at the same time.
I have found the same problem being present in PHP also. But those replies were related to PHP. Apache same orgin request blocking Why does apache not process multiple requests from the same browser simultaneously discusses about the same problem with php.
Related
So we are doing distributed testing of our web-app using JMeter. For that you need to have the jmeter-server.bat file running in background as it acts as sort of a listener. The problem arises when one of the slave machine out of 4 restarts due to the load and the test is effectively stuck right there as the master machine expects some output from the 4th machine. Currently the automation is done via ansible-playbooks which are called in Jenkins. There are more or less 15 tests that are downstream to one another. So even if one test is stuck, the time is wasted until someone check on the machines.
Things I've tried so far:
I've tried using the Windows Task Scheduler and kept the jmeter-server.bat to run without any user loggin in, but it starts the bat file in background which in-turn spawns all the child processes in the background as well i.e. starts Selenium Chrome in headless mode.
I've tried adding the jmeter-server.bat in startup and configuring the system to AutoLogon without any password to trigger a session which will call the startup file. But unfortunately the idea was scrapped by IT for being insecure.
Tried using the ansible playbook by using the win_command but it again gets stuck as the batch file never returns anything.
Created a service as well for the bat file, but again the child processes started in background.
The problem arises when one of the slave machine out of 4 restarts due to the load
Instead of trying to work around the issue I would rather recommend finding the root cause and fixing it.
Make sure to follow JMeter Best Practices
Configure Java to take heap dump on failure
Inspect Windows PerfMon and operating system/application logs
Check presence of .hprof files in the "bin" folder of your JMeter installation and see what do they say
In general using Selenium for conducting the load is not recommended, I would rather suggest using JMeter's HTTP Request samplers for that, given you properly configure JMeter to behave like a real browser from the system under test perspective there won't be any difference whether the load comes from HTTP Request samplers or from the real browser.
The same states documentation on the WebDriver Sampler
Note: It is NOT the intention of this project to replace the HTTP Samplers included in JMeter. Rather it is meant to compliment them by measuring the end user load time.
Problem
Sometimes important HTTP POST requests sent with AJAX got duplicated so several entries of the same data got created in the production database, that is of course not supposed by users.
What is important is that users have a poor internet connection and this request is taking a long time (9-20 seconds). We can't reduce this time because it is the requirements of business logic.
Requests are sent with http, not https.
Details
We have Apache/2.4.18 (Ubuntu) with PHP module loaded and two frontends: one for desktop (AngularJS) and one for mobile (React) devices. AngularJS is sending requests with the $http service, and React is using whatwg-fetch (tried whatwg-fetch-timeout also).
We know from Apache access.log and PHP logs that the same request is coming from the client several times and PHP processes them without the errors. But! These requests have response with 200 status code, %b > 0, and %O = 0, that means request is aborted before a response is sent (Apache logging format docs).
Reproduce
So we tried to reproduce and the same happens sometimes. The following case is just a reproduced case, but this happens on mobile devices (iPhones and Android phones) with different browsers installed. Also, we have repeated it in the Firefox under Windows.
Environment: Windows; both Chrome and Firefox; React frontend version; no proxy used.
That's what we found out: Google Chrome identifies the request as "Stalled", but is internally trying to send the request multiple times (and it is received and processed on the server actually), because it got the network error (ERR_CONNECTION_CLOSED). Only when the browser succeeded to fetch the response, it stops sending the repeating requests.
Gathered info
URL_REQUEST event log from chrome://net-internals/help.html#events (headers are also available there)
Google Chrome dev tools request screenshots:
Headers tab
Timeline tab
I personally can't reproduce this even once and I suppose a good internet connection is a reason for this.
I have googled a lot and even found some similar Chromium bugs, but nothing exactly about this problem.
Thank you in advance for any useful information.
I am also not pretty sure which tags should I set for this question, so if I should add or remove some, please tell me.
I have installed NIFI and when I run NIFI it starts well and shows the UI when accessed. I've made many flows. Different headers having different ports. Now what happens is, when I HIT using postman putting the specific header port such as localhost:10004/spec and gets it. Sometimes gets it, sometimes shows a 404 error and says no response but if clicked again to GET. It responds and then not. In short, nifi is constantly starting and stopping its services, but the nifi status shows that it's always running.
Latest logs:
I am running an Apache Server and I have placed a script to generate a report within the CGI-BIN which I can then start running from link in simple webpage I put together.
The script works no problem. What I have noticed though is that if I attempt to run two or more of the same script through the browser they are queued, i.e. the second will not run until the first is done? I was wondering why this happens and if it is possible to turn it off if necessary,
Thanks
It turns out that it was actually Chrome queueing the requests rather apache.
I tried it on different browsers and it worked fine.
HTTP requests of resources randomly - about between 1-5% of the time (per resource, not per page loads) - take extremely long to be delivered to the browser (~20 seconds), not uncommonly hanging indefinitely even. (Server details listed in list at the bottom).
This results in about every 5th request to any page appear to hang due to a JavaScript resource hanging within the <head> tag.
The resources are css, js and small image files, served directly by apache (no scripting language), although page loads (involving PHP or Rails) also rarely hang, with equal chances as any other resource (1-5% of the time), so this seems to be an Apache Request related issue.
Additional information:
I've checked the idle workers on server-status and as expected, I still have 98% of my idle workers. Although this may be relevant as the hangings apply to static resources not served by FastCGI (the resources are static).
I am not the only one with this problem. Someone else is also having the same problem, and from a different IP address.
This happens in both Google Chrome and Firefox as HTTP clients.
I have tried constantly force refreshing the same JS file in a new tab. It eventually led to the same kind of hanging.
The Timing tab for Google Chrome reports 34ms waiting and 19.27s receiving for one of these hanging requests. Would that mean Apache already had the file contents to be delivered ready, only had trouble delivering it in a sensible amount of time?
error.log doesn't show any errors. There are some expected 404 and 500 errors in error.log, but those aren't related to the hanging; those are actual errors for nonexisting pages and PHP fatal errors.
I get some suspicious 206 Partial Content responses mostly for static content, although the hanging happens more often then those partial contents. I mostly get 200 OK responses everywhere and I can confirm indefinitely hanging resources that were reported as 200 OK in the apache access.log.
I do have mod_passenger installed for Redmine. I don't know if that helps, but suspiciously this server has it installed unlike all the other servers I worked with. Although mod_passenger shouldn't affect static content, especially not within a non-ruby project folder, should it?
The server is using Apache 2.4 Event MPM on Ubuntu 13.10, hosted on Digital Ocean.
What may be causing these hangings and how could I fix this?
I had the same problem, so after reading this thread I tried setting KeepAlive Off in my apache config which seems to have helped- all resources have expected waiting times now.
Not a great "fix", but at least I am one step closer to figuring out the cause and pages aren't taking 15s to fully load in the mean time.