I did some research on this one and seems to be an issue for some users.
Noticed that Laravel logs me out automatically and intermittently. It's quite hard to replicate but it happened twice in a demo/presentation which has impact as you understand.
I can imagine that sessions can be suspect nr1 for this one but whatever I tried didn't seem to work.
How did you overcome this issue?
https://github.com/laravel/framework/issues/7549
On rare occasions, the session file can become corrupted if one copy reads in a half written out file. This condition, however, is difficult to reproduces.
Laravel team member #GrahamCampbell:
This is known limitation of the file based session driver.
Using a different session driver should do the trick. (My preference tends to be Redis, but the database driver may be a bit easier to set up for a demo.)
Related
It appears that in some very rare cases GetComputerName() Windows API returns 'TENTATIVE' as a computer name. Based on information from our customers we suspect that this sometimes happens on laptops when they 'awaken' from a sleep. The odd thing is that this happens after our app is already running and able to connect to a back-end server and retrieve some information from it - i.e. the computer name is written into a log file at the time.
We are considering putting a slight delay during 'awakaning' but would like confirm that the cause is what we suspect.
We could not find anything on-line that would confirm the source of the issue.
My VB6 program uses ADODB to do a lot of SQL (2000) CRUD.
Sometimes the network connection between the remote clients and the data center somehow "drops" resulting in the impossibility to establish new connections (so users launching the program can't use it).
The issue is the following:
Anyone who is using the program at the moment of the "drop" can continue using it with no issues whatoever, perform every operation, update data, read data, and everything seems like is working normally.
User then proceeds to fire up a "sum-up" report which lists everything that was done (before or after the "drop").
If we then check the database, all data regarding whatever was done after the network drop is not there. User goes back into the program and everything is as it was before the network drop.
It seems like all queries where somehow performed in-memory ? I'm at a loss about how to even approach the issue (I'm familiar enough with VB6 to work with the source code but I don't know a lot about ADODB).
I haven't yet tried to replicate the behavior due to limited customer's availability (development environment is housed in their offices), I'll try starting up the program from the IDE then rip out the network cable.
Provided I can replicate the issue, how do I fix this ? Is there some setting I'm not aware of ?
On a side note: the issue is sporadic (it happened a handful of times during the last year, and the software is being used heavily and on a daily basis by mutiple concurrent users).
After reading up on Disconnected Recordsets, it seems that's what's behind this odd behavior I'm experiencing.
This is not something that can be simply "turned off".
We have for some time now been experiencing problems with data being saved in our SQL database.
Sometimes records are saved with data that does not match the rest of the row, making it seem like at some point, data is being 'swapped' for something else, perhaps, another user's data, before being passed to the database.
We do use TransactionScopes throughout with Isolation Level of ReadCommitted which makes me think the data integrity issue lies within the application rather than at the Database level.
We do use the session extensively and we are starting to think that the times of the corrupt data are similar to the times we deploy updates to the system during the day.
We do use the aspnet_state service to persist the session over application restarts.
Our users rely on terminal sessions therefore multiple users all log into the same server and launch the system via a browser.
We have in the past noticed users logging in with the same domain credentials but we are now relatively confident that users now log in with unique accounts.
99.9% of the data is correct but we have been struggling to understand what could be causing this intermittent data integrity issue.
We are now limiting our deploys to outside working hours on pain of death, but this is not always possible.
Can anyone shed light on why/how this might be happening?
EDIT: We have now isolated this to the DAL layer, see SQL query returns incorrect value in multi user environment
I have recently been fighting this!, and had similar problem to yours around 95% of the data written back was correct. I looked at various reasons why, the main culprit was some users on the network had downloaded Chrome and opening the record within Chrome, breaking our session id's as Chrome ignores sessions.
The other cause had been either the users was not closing the browser or not logging off the application allowing either the same user or completely different user to pick and use the session id.
After introducing a browser check and then reject Chrome, educating the users to make sure they log off, doing any updates to outside busy periods the problem was just about gone.
I forgot to mention, also on your IIS its best to turn off caching in the Output Caching, for the user and kernal set to prevent caching.
We have a JPA -> Hibernate -> Oracle setup, where we are only able to crank up to 22 transactions per seconds (two reads and one write per transaction). The CPU and disk and network are not bottlenecking.
Is there something I am missing? I wonder if there could be some sort of oracle imposed limit that the DBA's have applied?
Network is not the problem, as when I do raw reads on the table, i can do 2000 reads per second. The problem is clearly writes.
CPU is not the problem on the app server, the CPU is basically idling.
Disk is not the problem on the app server, the data is completely loaded into memory before the processing starts
Might be worth comparing performance with a different client technology (or even just a simple test using SQL*Plus) to see if you can beat this performance anyway - it may simply be an under-resourced or misconfigured database.
I'd also compare the results for SQLPlus running directly on the d/b server, to it running locally on whatever machine your Java code is running on (where it is communicating over SQLNet). This would confirm if the problem is below your Java tier.
To be honest there are so many layers between your JPA code and the database itself, diagnosing the cause is going to be fun . . . I recall one mysterious d/b performance problem resolved itself as a misconfigured network card - the DBAs were rightly insistent that the database wasn't showing any bottlenecks.
It sounds like the application is doing a transaction in a bit less than 0.05 seconds. If the SELECT and UPDATE statements are extracted from the app and run them by themselves, using SQL*Plus or some other tool, how long do they take, and if you add up the times for the statements do they come pretty near to 0.05? Where does the data come from that is used in the queries, and which eventually gets used in the UPDATE? It's entirely possible that the slowdown is not the database but somewhere else in the app, such a the data acquisition phase. Perhaps something like a profiler could be used to find out where the app is spending its time.
Share and enjoy.
I have an application that uses coldfusion's session management (instead of the J2EE) session management.
We have one client, who has recently switched their company's traffic to us to come viaa proxy server in their network.
So, to our Coldfusion server, it appears that all traffic is coming from this one IP Address, for all of the accounts of this one company..
Of the session variables, Part 1 is kept in a cflock, and Part 2 is kept in editable session variables. I may be misundestanding, but we have done it this way as we modify some values as needed throughout the application's usage.
We are now running into an issue of this client having their session variables mixed up (?). We have one case where we set a timestamp.. and when it comes time to look it up, it's empty. From the looks of it this is happening because of another user on the same token.
My initial thoughts are to look into modifying our existing session management to somehow generate a unique cftoken/cfid, or to start using jsession_ID, if this solves the problem at all.
I have done some basic research on this issue and couldn't find anything similar, so I thought I'd ask here.
Thanks!
I've run into similar problems on and off for years.
JSession cookies seem to help (no hard data on that) but one solution that I've implemented repoeatedly is using no-cache and cache expiry headers on every page.
http://www.bpurcell.org/blog/index.cfm?entry=1075&mode=entry gives some specifics on how to implement this.
In extreme cases, we've been forced to pass the token and cfid in the links/forms, but that is a PITA to implement, so I'd try the cache expiry/prevention soluiton first.
As far as I know, there are no "cons" in using J2EE session variables, unless you really need session to be active after user closes the browser. I think you should try and see how application behaves with it and see if that saves you trouble of refactoring.
To be sure that you are using all other settings try this:
<cfdump var="#APPLICATION.GetApplicationSettings()#" label="Application settings" />
If you have sessionmanagement and client cookies turned on, everything is fine, so try j2ee session variables.