I have a Linux Server (CentOS) with 32GB RAM.
I installed the MongoDB with a Java application. But sometimes, the MongoDB stops to work. So I need to restart it.
I already used the ulimit linux command to change te open files limit to 64000, but the problem still happens.
I'd like to know if somebody have some experience with MongoDB and can give me some tip about this problem.
If you're getting "too many connections," it's quite possible you're opening too many MongoClients. In general, you need only open the one client and its internal connection pool will manage everything for you. This isn't always possible, though, so you'll want to make sure you properly manage the scope of each MongoClient and call close() on it when you're done.
Related
I am using ORACLE database in a windows environment and running a JSP/servlet web application in tomcat. After I do some operations with the application it gives me the following error.
ORA-12518, TNS: listener could not hand off client connection
can any one help me to identify the reason for this problem and propose me a solution?
The solution to this question is to increase the number of processes :
1. Open command prompt
2. sqlplus / as sysdba; //login sysdba user
3. startup force;
4. show parameter processes; // This shows 150(some default) processes allocated, then increase the count to 800
5. alter system set processes=800 scope=spfile;
As Tried and tested.
In my case I found that it is because I haven't closed the database connections properly in my application. Too many connections are open and Oracle can not make more connections. This is a resource limitation. Later when I check with oracle forum I could see some reasons that have mentioned there about this problem. Some of them are.
In most cases this happens due to a network problem.
Your server is probably running out of memory and need to swap memory to disk.One cause can be an Oracle process consuming too much memory.
if it is the second one, please verify large_pool_size or check dispatcher were enough for all connection.
You can refer bellow link for further details.
https://community.oracle.com/message/1874842#1874842
I ran across the same problem, in my case it was a new install of the Oracle client on a new desktop that was giving the error, other clients were working so I knew it wouldn't be a fix to the database configuration. tnsping worked properly but sqlplus failed with the ora-12518 listener error.
I had the tnsnames.ora entry with a SID instead of a service_name, then once I fixed that, still the same error and found I had the wrong service_name as well. Once I fixed that, the error went away.
If from one day to another the issue shows for no apparent reasons, add these following lines at the bottom of the listner.ora file. If your oracle_home environment variable is set like this:
(ORACLE_HOME = C:\oracle11\app\oracle\product\11.2.0\server)
The lines to add are:
ADR_BASE_LISTENER = C:\oracle11\app\oracle\
DIRECT_HANDOFF_TTC_LISTENER=OFF
I had the same problem when executing queries in my application. I'm using Oracle client with Ruby on Rails.
The problem started when I accidentally started several connections with the DB and didn't close them.
When I fixed this, everything started to work fine again.
Hope this helps another one with the same problem.
I experienced the same error after upgrading to Windows 10. I solved it by starting services for Oracle which are stopped.
Start all the services as shown in the following image:
I had the same issue. After restarting all Oracle services it worked again.
same problem encountered for me.
And from oracle server listener log, can see more information.
and I found that the SERVICE_NAME is not match the tnsnames.ora configured Service name. so I changed the application's data source configuration from SID value to Service_NAME value and it fixed.
23-MAY-2019 02:44:21 * (CONNECT_DATA=(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=XXXXXX$))(SERVICE_NAME=orclaic)) * (ADDRESS=(PROTOCOL=tcp)(HOST=::1)(PORT=50818)) * establish * orclaic * 12518
TNS-12518: TNS:listener could not hand off client connection
TNS-12560: TNS:protocol adapter error
TNS-00530: Protocol adapter error
64-bit Windows Error: 203: Unknown error
I had the same issue in real time application and the issue gone by itself next day. upon checking, it was found that server ran out of memory due to additional processes running.
So in my case, the reason was server run out of memory
first of all
check the listener log
check the show parameter processes vs select count(*) from v$processes;
increase the process, it may require SGA increase
;
I have an application that is using the upper.io/db package for communication with a Mongo database server (which is a fairly simple wrapper around gopkg.in/mgo.v2). The way the application works is that it creates a session in the main thread on start-up, and then each individual go routine that needs to make requests to the mongo server calls Clone on the session and does a defer session.Close on the resulting value. As far as I can tell, this is all standard operating procedure.
This setup works without any errors in our development environments where we are either using a locally run MongoDB or a sandbox instance on MongoLab. Recently we promoted the application up to our staging environment where we have the application talking to a Shared Cluster instance of MongoDB on MongoLab (the cheapest 15$ option). This is where the weirdness starts happening. The /first/ request that goes through (from the first go-routine that gets invoked) comes back with the expected response, but the subsequent ones all return
read tcp <ip address>:47112: i/o timeout
This happens both from our local development machines pointed at the cluster or from the AWS host for the staging environment. Since the Mongo cluster is from Mongolabs I am going to assume that they've configured everything correctly on their end.
The code is somewhat boring TBH: It literally just opens the session in the main function and maintains a reference to it, and then there are multiple goroutines with this basic structure:
sess := session.Clone()
defer sess.Close()
// make requests to Mongo
During testing, I even restricted it to run only one thing at once (i.e. only one goroutine is active at any given time), and it still fails in the same fashion.
Has anybody run into this before? Do I need to configure upper.io/db in a specific fashion? Maybe use mgo directly? I am at my wits end with this :(
In a rather long and grueling process, we finally tracked down where this issue and similar ones like it came from in our program. It ended up being a session leak in the v1 version of the upper.io/db library. The bug and fix are outlined here, but the v1 version of this library is horribly outdated at this point and the later versions do not exhibit this issue.
I doubt this answer will be useful for anybody so late in the game (especially since we ourselves solved it like.. 3 years ago at this point), but just wanted to leave the answer here for completeness.
I've followed instructions online to set up a Telescope instance on my DigitalOcean droplet, but it won't start with Upstart.
I'm able to run the server successfully manually, but the Upstart task doesn't fire when the server boots. I'm sure I should be looking at a log file somewhere to discover the problem, but I'm not sure where.
I've looked for the location of upstart logs, but I'm not having any luck. Either you have to add something to your script to make it log, or it just does it according to accounts online, but neither of those seem to be the case for me.
When I try to search for help on Upstart, I'm also seeing people saying I should be using systemd instead, but I can't figure out how to install it on CentOS 6.5.
Can anyone help me figure a way out of this labyrinth?
I use Ubuntu server 14.04, and my upstart logs are located in /var/log/upstart
The log usually contains stdout from the job, and it should help you understand what's wrong.
My guess is that when the server boots and tries to run your job, MongoDB is not yet ready so it fails silently.
Try installing the specific MongoDB version that Meteor is using at the moment (2.4.9) using these docs :
http://docs.mongodb.org/v2.4/tutorial/install-mongodb-on-ubuntu/
The most important thing is to get upstart support for MongoDB, this will allow us to catch mongod launch as an event.
You can then use this syntax in your upstart script :
start on started mongodb
This will make your node app start when mongo is ready.
I've created a gist with the scripts I wrote to setup a server ready for Meteor app deployment, it's a bit messy and probably specific to Ubuntu but it might help you.
https://gist.github.com/saimeunt/4ace7975b12df06ee0b7
I'm also using demeteorizer and forever which are two great tools you should probably check.
I'm writing an new version of a website using fuel PHP 1.5 and mongodb 2.4.3. Right now we're just getting the initial batch of pages set up to verify that the technology works. The issue that I'm running into, and this is more so an issue for my coworkers then myself, is that periodically it just won't connect to the server. It returns a generic -
"Fuel\Core\Mongo_DbException [ Error ]: Unable to connect to MongoDB: Failed to connect to: 166.78.248.139:27017: Timed out after 0 ms"
but... if you refresh the page this often goes away. I should mention that the overall DB size right now is tiny, (we're using 'newsite'): [
otherhook 0.203125GB
local 0.078125GB
newsite 0.203125GB
test 0.203125GB
]
and the server has 2GB of RAM. There are a grand total of 3 of us trying to connect to and use the box. I might also add that I've only seen this error once the 3rd person started working on it, but not before. ...alright that's as much information as I've got.
Anyone have any ideas as to what's really causing this? Any idea on how to fix it so that we don't have these intermittent connection errors?
Take a look in the MongoDB logs, and in particular look for issues with it running out of resources when trying to open connections (there will usually be a warning printed at start up too relating to ulimits being too low or similar). You haven't mentioned what OS you are running on, but if it Linux, then the settings you are looking for are documented here:
http://docs.mongodb.org/manual/reference/ulimit/
For OS X, take a look here:
https://superuser.com/questions/433746/is-there-a-fix-for-the-too-many-open-files-in-system-error-on-os-x-10-7-1
I’m working on a experiment regarding to a course I’m taking about tuning DB2. I’m using the EC2 from Amazon (aws) to conduct the experiment.
My problem is, however, that I have to test a non-compression against row-compression in DB2 and to do that I’ve created a bsh file that run those experiments. But when I reach to my compression part I get the error ”Transaction log is full”; and no matter how low I set the inserts for it is complaining about my transaction log.
I’ve scouted Google for a day now trying to find some way to flush / clear the log or just get rit of it, i don’t need it. I’ve tried to increase the size but nothing has helped.
Please, I hope someone has an answer to solve this frustrating problem
Thanks
- Mestika
There is no need to "clear the log" in DB2. When a transaction is rolled back, DB2 releases the log space used by the transaction.
If you've increased the log size and it has not helped, please post more information about what you're trying to do.
No need of restarting. Just try to force the applications using DB2 force applications all.
Increase the Actie Log File Size and try to force application connections and terminate the connections.
Try to run the job now.
db2 force applications all
db2 update db cfg for sample using logfilsiz 5125
db2 force applications all
db2 terminate
db2 connect to sample
Run your job and monitor.
Just restart the instance, it would release the pending logs and you should be fine