I'm not quite sure how to phrase this question correctly, so I'll start with the scenario I encountered.
I have a bit of processing in my web app that takes longer than I'd like the user to wait to have control of the page again, so I decided to have it processed by an ajax request.
The problem is, even though I offloaded this request into an ajax request, it seems that apache won't process any further requests until the original processor heavy request is complete.
I originally wanted to know how I could get around this issue, but have since decided that it might be a bad idea in general.
However, I'm still curious if anyone knows why apache behaves this way, and what (if any) configuration directive controls it. My original thought was KeepAlive, but disabling that didn't seem to change the behavior.
I am running php through mod_php if that makes a difference.
I appreciate any help getting pointed in the right direction!
Are you using file-based sessions? PHP will lock session files for each request and maintain that lock until you do a session_write_close() or the script terminates/exits. The side effect of this is that all requests become serial, since they're all contending for the same single resource (the session file).
I am sure it's the session file. I have the same problem. I run a request that is long such as a PHPMyAdmin SQL insert which takes multiple minutes to process. While it is processing I try to open a new tab in the same browser and go to any page on my website and it will not go there until the original PHPMyAdmin request is done.
If I open an incognito window in Chrome which is the same browser it works fine. If I open the website in any other browser it is fine.
So it is probably the file based session which is the default for PHP.
Others have mentioned going to memcached. You could also save sessions in the database.
Before having to go to memcached you could do all the session based stuff at the beginning. Copy the session variable into a temporary variable so you can close it then close it. And then if you need to set a session value later open it and make the change and then close it quickly.
Can you point to evidence that it's apache? Unless your apache setup isn't optimal, most likely your page wait is something else, maybe you have set your ajax call to be non-async?
Related
Hoping someone has some ideas around what to do with this.
We have a application thats PHP based hosted in IIS.
There are a number of functions that need to run which can be running for 10mins+. The problem I have is that if I run one of these functions in my web browser. If I open another tab and try to access the site while that is happening then it just sits loading until the long process finishes and then it loads the page.
I guess this is more of a multi session thing to my browser? Is there some easy option in IIS I can change that will let it load the other pages as normal? Or is this a browser thing?
It seems if I open an in private window at the same time, that will load normally.
The issue is related to the session. by default PHP session use a file system.so that has to wait for the session file to be closed before they can open new. Therefore, subsequent requests for the same session wait on prior requests.
To resolve the issue you could try the below things:
-close the session when you are done with it by using the session_write_close()
-Implement a custom DB handler which utilizes the database instead of the file system.
Reference:
FastCGI on IIS7... multiple concurrent requests from same user session?
Not all the time, but sometimes if I visit the site as this http://WEBSITESAMPLE.com/paramA/pathB/, it becomes very slow and nothing loads till a minute or so, but if I add something dummy on the path, it loads immediately, do any of you have an idea why is it?
I am not sure what's going on here because your question lacks a little detail.
But just to make the scenario clear when it comes to Client/ Server side and accessing something on the web with a domain. You have to understand that whatever lags you experience it always points to a certain process that a line of code cannot finish the job in the desired time.
Lags sometimes caused by a script like Javascript(JS) that probably will send request from the server which server can't response in a certain time required by the script.
Also sometimes, browsing to a specified URL without a clear path to a server could cause waiting time.
anyhow, you have to inspect the path you are accessing and the source code and possible process jobs. From there I'm sure you can figure it out.
Otherwise you have to share your setup. Assuming you're the one who setup and build the site.
I have a website (www.mysite.com) with a private backend (www.mysite.com/admin)
When I'm adding content to the site in the admin area and switch back and forth between tabs in the same browser window to see the content I'm editing, my session is getting expired/ended/terminated and I'm redirected to the login page again.
I have used the same code many-many times before on many web sites (this is a CMS I've made by myself) without a problem. The only thing I can think of is that this particular website is hosted on a different web server and maybe it's a matter of a php.ini setting or server configuration. Any ideas?
Have you checked your browser cookies? (the actual client-side ones?) or tried your luck with another browser? It may sound a bit strange, but I had a similar problem and in my case it had to do with these cookies. It may be worth figuring out because of your odd problem. As you might know the phpsession value is stored in that cookie and so is the domain.
Good luck!
This could be a result of several things, but my first instinct is to check and see if the session cookies are expiring very quickly. Sometimes server headers may change expiry values. You may also want to check the cache headers being sent by the server. If you are using asynchronous functionality on the admin area, it is possible that somehow the server is changing the expiry of cached files which could affect this.
I am eager to see the solution to this.
A few things to check:
session.cookie_lifetime setting - Possibly too short; 0 is the default and keeps the cookie until the browser closes
session.cookie_path setting - You'll want this to be '/'
Session storage - Make sure the session data is being written.
Explicitly call session_close() if your sessions are stored in a database. That will ensure they are written before your objects and database resources are destroyed.
If serving through any sort of proxy, check for any changed header information.
If caching, check your dynamic pages (requiring sessions) are being served by your web app and not the cache.
If testing with your local /etc/hosts, first clear your cookies so the new server's cookies are fresh and don't conflict.
Confirm in your browser that the cookie is in fact being stored. Maybe it's not actually coming back in the header.
I had a problem like this before. I was just uploaded a site from my localhost to a remote host, and I haven't change the nameservers yet. The hosting company provided me with a temporary url to be able to see my website. The problem was that this url was like this https://server_name.grserver.gr:8443/sitepreview/http/my_site.gr/, the result was that any browser didn't accepted the session cookie because I didn't had an SSL sertificate so the sessions didn't worked at all. I browsed a little the plesk panel and I found an other temporary url that was using http protocol, with this everything was ok. So if you are using https try to check if you have a problem with your ssl sertificate (for expample if it has expired). You said the problem occurs when you login in the admin page, do you switch then to https?
There could be several reasons. As there is no code or no details about the site provided , I am assuming that the problem might be if you are using htpasswd. If u are using htaccess authentication, then your session gets destroyed.
From experience, I can tell you a few things.
First, sessions need to be started with
session_start();
At the top of every page you want to use sessions.
Next, to save session data, you need to call another function to tell php that you are saving stored data. That function is
Session_write_close();
That function is needed on the bottom of the page when you are finished writing data to a session and want it saved for later use.
With those two combined, that should allow you to properly write to a session, save the data you entered into it, and access it later on your site.
Good luck.
The problem has been found after reading this topic.
I had a custom php.ini in the root dir and apparently it was interfering with the $_SESSION. I don't know why but after deleting it everything works fine.
At first it seemed as if the problem was opening pages located in different sub-folders in several browser tabs however it narrows down to a sub-folders issue and the fact that the $_SESSION wasn't accessible across them.
I'd like to thank everyone that put some time into trying to help me figure this out.
I've been trying to track down some annoying session issues since my webhost upgrade to PHP 5.3.3 awhile back. I've determined that if there is an active session, calling session_start() from a subdirectory kills the existing session. As an example, I start a session and a user logs in to domain.com/index.php then the user navigates to domain.com/members/ which fires start_session() ... the user's session is lost.
I've dug around for this and can't find anything similar. Is there a PHP configuration that would account for this behavior?
Calling session_start() multiple times with that version of PHP shouldn't cause any problems, however there are other possible causes.
One possible explanation is that the client's browser isn't sending the session id back to the server. You can test this out by comparing the session id that both pages produce. Assuming that you have a controlled environment where you can test this properly, you can use session_id() to get the session.
It might also be that the user is hitting a different webserver. Since (by default) PHP stores sessions to disk, there is no way for multiple servers to share the session information. If this is a shared host, it's probably quite unlikely this is the cause. You can test this out however by using phpinfo(). It should give you enough information to determine if it's the same server or not. For multi-server systems, I'd look at storing sessions in memcache or mysql.
if your sessions works all right within the same directory (it is unclear from your question), there is the only possible reason for such a behavior, a pretty obvious one: "directory" cookie parameter.
It seems it is set to somewhat unusual value, other than default "/" for the session cookie parameter.
You have to check it out.
Anyway, it is almost useless to try ANY session/cookie related problem without an HTTP interchange log.
You have to use some HTTP sniffer, like LiveHTTPHeaders Firefox addon to see what cookie header was sent by the server and which one was returned by client.
Otherwise it's all going to be shooting in the dark.
Okay, as it seems from your yonder comment, the session id remains the same, so, no HTTP issue can be a reason. The issue become a kinda tricky to spot.
Could you please post your test script here?
I've spent quite a long time searching, trying, testing for what looked like the same problem. As google kept sending me here, I think sharing the solution might help others (though I feel strange posting on a 2011 question):
Session variables set in /bar.php were not set in /foo/foobar.php.
It realised that the issue had nothing to do with folder/subfolder when I finally found out that the link in http://www.example.com/bar.php was pointing to http://example.com/foo/foobar.php (missing www).
Correcting the URL in the html link solved the problem. Having no time to dig deeper, what I can figure out is that (in my config) Apache makes no difference and serves pages indifferently with and without www, whereas PHP doesn't share the session between what it considers being two different domains, example.com and www.example.com.
Is there a PHP configuration that would account for this behavior?
Yes, if the storage for the session data differs between those calls, the $_SESSION content will differ as well. The storage can be configured, see http://php.net/manual/en/session.configuration.php for all configuration options you have with sessions.
Next to that if PHP is unable to read the session store, you will get an empty array as well.
I can't tell you if this is the issue with your problem, but probably it's helpful.
BTW, calling session_start() and than having an empty $_SESSION is commonly a sign that a new session has been created. You can verify this if you use cookies for your sessions and you output headers_listDocs:
echo '<pre>', var_dump(headers_list());
If it contains a new cookie for the session, the session has been created with this request.
Lots of good suggestions here. Thanks everyone. I spent a good chunk of the weekend digging into this and wasn't able to directly resolve it. I ended up demonstrating to my webhost that this problem happens on two of his hosted sites and doesn't happen in a default install of PHP. To work around the problem, I ended up moving all of my login and session logic into a single class.
Wanted to share another answer, found in this SO: Session variables not accessible in subdirectory answered by clayRay.
My answer was that I had a custom "php.ini" file saved in the root directory, and moving those directives into ini_set() calls solved it. You could also shove those over to .htaccess if your host allows.
Totally confused by this one...
We have a WAMPServer installation set up, running a number of virtual hosts from various document roots.
Just recently, one particular domain has started hanging the server. We traced it down to session_start(). If we comment it out, there are no problems (except, of course, for the fact that we can't do anything with the session). With it uncommented, it will hang the page load and, with enough reloads, will hang the entire server.
All of the other sites still work perfectly with their sessions. As far as I know, there is nothing different with the way sessions are being worked with. I am looking further into it (in case someone changed something) but right now I'm hoping for some direction :)
So, any thoughts?
So, I'm guessing that it's an application layer problem because the other sites' sessions are working properly. However, this assumes that they have their sessions configured the same way - save yourself some time by double checking that your site isn't doing some "unique" in its configuration compared to the other sites.
I would next examine the other session related code that is running in your application. It could be that by calling session_start() you're putting your application into a state where it will run other code. For example, maybe there's a block of code that says "only run this function if this session variable is set" and by starting the session you're exposing that variable, where it wouldn't have been exposed and therefore not run the offending function if the session wasn't started.
Good luck.
My first guess would be file permissions if you are using file based sessions. If you are using database sessions, then I would check to make sure a table isn't corrupt. Also, is it Apache, PHP or something else that's locked up?
It's possible that you hit a bug in your underlying infrastructure that you won't be able to resolve. You should at least clear all existing sessions before moving forward with trying to diagnose this.