1167:M 26 Apr 13:00:34.666 # You requested maxclients of 10000 requiring at least 10032 max file descriptors.
1167:M 26 Apr 13:00:34.667 # Redis can't set maximum open files to 10032 because of OS error: Operation not permitted.
1167:M 26 Apr 13:00:34.667 # Current maximum open files is 4096. maxclients has been reduced to 4064 to compensate for low ulimit. If you need higher maxclients increase 'ulimit -n'.
1167:M 26 Apr 13:00:34.685 # Creating Server TCP listening socket 192.34.62.56:6379: Name or service not known
1135:M 26 Apr 20:34:24.308 # You requested maxclients of 10000 requiring at least 10032 max file descriptors.
1135:M 26 Apr 20:34:24.309 # Redis can't set maximum open files to 10032 because of OS error: Operation not permitted.
1135:M 26 Apr 20:34:24.309 # Current maximum open files is 4096. maxclients has been reduced to 4064 to compensate for low ulimit. If you need higher maxclients increase 'ulimit -n'.
1135:M 26 Apr 20:34:24.330 # Creating Server TCP listening socket 192.34.62.56:6379: Name or service not known
Well, it's a bit late for this post, but since I just spent a lot of time(the whole night) to configure a new redis server 3.0.6 on ubuntu 16.04. I think I should just write down how I do it so others don't have to waste their time...
For a newly installed redis server, you are probably going to see the following issues in redis log file which is /var/log/redis/redis-server.log
Maximum Open Files
3917:M 16 Sep 21:59:47.834 # You requested maxclients of 10000 requiring at least 10032 max file descriptors.
3917:M 16 Sep 21:59:47.834 # Redis can't set maximum open files to 10032 because of OS error: Operation not permitted.
3917:M 16 Sep 21:59:47.834 # Current maximum open files is 4096. maxclients has been reduced to 4064 to compensate for low ulimit. If you need higher maxclients increase 'ulimit -n'.
I have seen a lot of posts telling you to modify
/etc/security/limits.conf
redis soft nofile 10000
redis hard nofile 10000
or
/etc/sysctl.conf
fs.file-max = 100000
That might work in ubuntu 14.04, but it certainly not works in ubuntu 16.04. I guess it has something to do with changing from upstart to systemd, but I am no expert of linux kernel!
To fix this you have to do it the systemd way
/etc/systemd/system/redis.service
[Service]
...
User=redis
Group=redis
# should be fine as long as you add it under [Service] block
LimitNOFILE=65536
...
Then you must daemon reload and restart the service
sudo systemctl daemon-reload
sudo systemctl restart redis.service
To check if it works, try to cat proc limits
cat /run/redis/redis-server.pid
cat /proc/PID/limits
and you will see
Max open files 65536 65536 files
Max locked memory 65536 65536 bytes
At this stage, the maximum open file is solved.
Socket Maximum Connection
2222:M 16 Sep 20:38:44.637 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
Memory Overcommit
2222:M 16 Sep 20:38:44.637 # Server started, Redis version 3.0.6
2222:M 16 Sep 20:38:44.637 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
Since these two are related, we will solve it at once.
sudo vi /etc/sysctl.conf
# Add at the bottom of file
vm.overcommit_memory = 1
net.core.somaxconn=1024
Now for these configs to work, you need to reload the config
sudo sysctl -p
Transparent Huge Pages
1565:M 16 Sep 22:48:00.993 # WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis. To fix this issue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain the setting after a reboot. Redis must be restarted after THP is disabled.
To permanently solve this, follow the log's suggestion, and modify rc.local
sudo vi /etc/rc.local
if test -f /sys/kernel/mm/transparent_hugepage/enabled; then
echo never > /sys/kernel/mm/transparent_hugepage/enabled
fi
This require you to reboot, backup your data or do anything you need before you actually do it!!
sudo reboot
Now check you redis log again, you should have a redis server without any errors or warnings.
Redis will never change the maximum open files.
This is a OS configuration and it can be configured on a per user basis also. The error is descriptive and tells you: "increase 'ulimit -n'"
You can refer to this blog post on how to increase the maximum open files descriptors:
http://www.cyberciti.biz/faq/linux-increase-the-maximum-number-of-open-files/
You just need this command in console:
sudo ulimit -n 65535
Related
Sorry redis newbie here.
When I run redis-sentinel
42533:X 10 Nov 21:21:30.345 # Warning: no config file specified, using
the default config. In order to specify a config file use redis-
sentinel /path/to/sentinel.conf
42533:X 10 Nov 21:21:30.346 * Increased maximum number of open files to
10032 (it was originally set to 7168).
Redis 3.0.4 (00000000/0) 64 bit
Running in sentinel mode
Port: 26379
PID: 42533
http://redis.io
42533:X 10 Nov 21:21:30.347 # Sentinel runid is
733213860cf470431c7441e5d6aaf9ed9b2d7c2f
42533:X 10 Nov 21:21:30.347 # Sentinel started without a config file.
Exiting...
What am I missing? Do I need a configuration file? If so where should my /path/to/sentinel.conf be?
It is mandatory to use a configuration file when running Sentinel, as this file will be used by the system in order to save the current state that will be reloaded in case of restarts. Sentinel will simply refuse to start if no configuration file is given or if the configuration file path is not writable.
you can run Sentinel with the following command line:
redis-sentinel /path/to/sentinel.conf
Otherwise you can use directly the redis-server executable starting it in Sentinel mode:
redis-server /path/to/sentinel.conf --sentinel
You can put the file anywhere you want, just make sure you are providing the right path for that. For example, if you are in linux and if the file is inside your home directory, then the command will be
redis-sentinel ~/sentinel.conf
I am getting this error while connecting redis-cli. Please help me to fix this.
tony#kali:~$ redis-cli
Could not connect to Redis at 127.0.0.1:6379: Connection refused
Could not connect to Redis at 127.0.0.1:6379: Connection refused
not connected>
i learned my mistake what was i did was first i started redis-server when that show i'm connected to port i pressed ctrl + c in keyboard then i tried to start redis cli but later i got it after several attempt that i have to use this command to start redis
redis-server & redis-cli
If you installed redis with brew, you have to do the following first:
brew services start redis
I got the following error on first attempt to start the redis-server:
********************
22:M 17 May 2020 11:00:58.705 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
22:M 17 May 2020 11:00:58.706 # Server initialized
22:M 17 May 2020 11:00:58.707 # WARNING overcommit_memory is set to 0!
Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
22:M 17 May 2020 11:00:58.710 *
Ready to accept connections
not connected>
*********
i modified the 'sysctl.conf' file and added the line .. reloaded the Ubuntu App. It resolved the issue.
68:M 17 May 2020 11:09:35.023 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
68:M 17 May 2020 11:09:35.027 # Server initialized
68:M 17 May 2020 11:09:35.028 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
68:M 17 May 2020 11:09:35.032 * Ready to accept connections
root#US-00008275:~# redis-cli
127.0.0.1:6379> set user1:SP
(error) ERR wrong number of arguments for 'set' command
127.0.0.1:6379> set user1:1 "SP"
OK
127.0.0.1:6379> get user1:1
"SP"
127.0.0.1:6379>
Run the below command and then try redis-cli
sudo apt-get install redis-server
We are on 16GB AWS instance and I am finding it to be really slow. When I ran
ps -aux | grep apache
I can see about 60+ apache processes.
When I ran
watch -n 1 "echo -n 'Apache Processes: ' && ps -C apache2 --no-headers | wc -l && free -m"
It is showing almost all memory being used by apache.
When I ran
curl -L https://raw.githubusercontent.com/richardforth/apache2buddy/master/apache2buddy.pl | perl
to see how to optimize Apache, it suggested me to increase number of MaxRequestWorkers so I made it 550. I also changed MaxConnectionsPerChild from 0 (unlimited) to 10000.
Here is my /etc/apache2/mods-enabled/mpm_prefork.conf file
<IfModule mpm_prefork_module>
StartServers 5
MinSpareServers 5
MaxSpareServers 10
MaxRequestWorkers 550
MaxConnectionsPerChild 10000
</IfModule>
Can you tell me how can we optimize apache memory usage so it don't bring down the whole site down ?
I had a similar problem with an instance in EC2 and here's what I did and would suggest:
If you are using prefork, make sure that the module is loaded by typing these two commands
apache2 -l and sudo apache2 -M
If you can see the prefork module loaded in the results of either of these two commands then up to the next step. Otherwise, make sure to load it first or else you would be changing the configurations for nothing.
Run this command to find the average memory each apache2 process is using ps aux | grep 'apache2' | awk '{print $6/1024;}' | awk '{avg += ($1 - avg) / NR;} END {print avg " MB";}' Call that value x
Restart your apache server by using sudo service apache2 restart and take a note of how much free memory you have. What I did was subtract an extra 200MB-500MB cushion from that free memory to be used later. Call that value y
Divide the value of free memory y over the amount of memory used per process x and that would be the value of MaxRequestWorkers = y/x
As for the value of MaxConnectionsPerChild then you can tweak it till you get the right configuration. It you make it too big, then the process will keep using more and more memory before being killed. If you make it too small, then the processes will die too quickly and that will present an overhead on your system. I usually keep it somewhere between 4000 and 10000.
Some of these steps have been taken from the accepted answer in the following link: StackExchange: httpd memory usage where one solution also suggested disabling some of the modules if you don't need them.
I would suggest you do steps 1-5 first and see if that solves your problem!
Good luck!
I get the following error, whenever I execute any commands that modify data in redis
Redis is configured to save RDB snapshots, but is currently not able to persist on disk.
Commands that may modify the data set are disabled.
Please check Redis logs for details about the error.
I installed redis using brew on mac. How can I get the location of log files where redis-server logs information to. I tried looking for redis conf. file, but couldn't find it either.
What is the default location of [1] redis conf file [2] redis log file.
How do I get rid of the above error, and be able to execute commands that modify data in redis.
When installing with brew the logfile is set to stdout. You need to edit /usr/local/etc/redis.conf and change logfile to something else. I set mine to:
logfile /var/log/redis-server.log
You'll also make sure the user that runs redis has write permissions to the logfile, or redis will simply fail to launch completely. Then just restart redis:
brew services restart redis
After restarting it'll take a while for the error to show up in the logs, because it happens after redis fails its timed flushes. You should be seeing something like:
[7051] 29 Dec 02:37:47.164 # Background saving error
[7051] 29 Dec 02:37:53.009 * 10 changes in 300 seconds. Saving...
[7051] 29 Dec 02:37:53.010 * Background saving started by pid 7274
[7274] 29 Dec 02:37:53.010 # Failed opening .rdb for saving: Permission denied
After a brew install it attempts to save to /usr/local/var/db/redis/ and since redis is probably running as your current user and not root, it can't write to it. Once redis has permission to write to the directory, your logfile will say:
[7051] 29 Dec 03:08:59.098 * 1 changes in 900 seconds. Saving...
[7051] 29 Dec 03:08:59.098 * Background saving started by pid 8833
[8833] 29 Dec 03:08:59.099 * DB saved on disk
[7051] 29 Dec 03:08:59.200 * Background saving terminated with success
and the stop-writes-on-bgsave-error error will no longer get raised.
So I guess it is a bit late for adding an answer here but since I wondered on your question as I had the same error. I got it solved by changing my redis.conf 's dir variable like this:
# The filename where to dump the DB
dbfilename dump.rdb
# The working directory.
#
# The DB will be written inside this directory, with the filename specified
# above using the 'dbfilename' configuration directive.
#
# The Append Only File will also be created inside this directory.
#
# Note that you must specify a directory here, not a file name.
dir /root/path/to/dir/with/write/access/
The default value is: ./, so depending on how you launch your redis server you might not be able to save snapshots.
Hope it helps someone !
In my case i resolved this issue with below steps
Cause : By default redis store data # ./ and if redis runs with redis user this means redis will not be able to write data in ./ file then you will face above error.
Resolution :
Step # 1 (Enter a valid location where redis can do write operations)
root#fpe:/var/lib/redis# vim /etc/redis/redis.conf
dir /var/lib/redis # ( This location must have right for redis user to write)
Step # 2 (Connect to redis cli and map directory to write and issue below variable)
127.0.0.1:6379> CONFIG SET dir "/var/lib/redis"
127.0.0.1:6379> BGSAVE -
This will enable redis to write data on dump file.
Was going through the github discussion and the proposed solution is
to run
config set stop-writes-on-bgsave-error no
in the redis-cli.
here's the link
https://github.com/redis/redis/issues/584#issuecomment-11416418
Steps to fix this error:
Go to redis cli by typing redis-cli
127.0.0.1:6379> config set stop-writes-on-bgsave-error no
after that try to set key value
127.0.0.1:6379> set test_key 'Test Value'
127.0.0.1:6379> get test_key
"Test Value"
Check the following places:
/usr/local/Cellar/redis...
/usr/local/var/log/redis.log
/usr/local/etc/redis.conf
This error often indicates an issue with write permissions, make sure you're RDB directory is writable.
It is usually because permission limits. In my case, it's redis disabled write options.
You can try to run redis-cli in the shell, and then run the following command:
set stop-writes-on-bgsave-error yes
I've got redis installed on my VM, and I haven't used it in a while. (Last I was using it, it did work, and now it doesn't.. nothing's changed in that time (about a month)). Needless to say I'm deeply confused but I'll post as much info as I can.
$ redis-server
Server starts, but throws a warning about overcommit memory being set to 0. I'm on a VM, so I can't change this setting from 0 to 1 if I wanted, which I wouldn't want to anyway for my purposes. I've written a custom redis.config file though, which I want it to use (and which I was using in the past), so starting it with the default config file doesn't do me much good. Let's try this again.
$ redis-server redis.config
$
Nothing. Silence. No error message, just didn't start.
$ nohup redis-server redis.config > nohup.out&
I get a process ID, but then $ ps and I see the the process is listed as stop and shortly disappears. Again, no errors, and no output in nohup.out nor in the log file for redis. Below is the redis.config I'm using (without the comments to keep it short)
daemonize yes
pidfile [my-user-account-path]/redis/redis.pid
port 0
bind 127.0.0.1
unixsocket [my-user-account-path]/tmp/redis.sock
unixsocketperm 770
timeout 10
tcp-keepalive 60
loglevel warning
logfile [my-user-account-path]/redis/logs/redis.log
databases 16
save 900 1
save 300 10
save 60 10000
stop-writes-on-bgsave-error no
rdbcompression no
rdbchecksum no
dbfilename dump.rdb
dir [my-user-account-path]/redis/db
slave-serve-stale-data yes
slave-priority 100
appendonly no
lua-time-limit 5000
slowlog-log-slower-than 10000
slowlog-max-len 128
# ADVANCED CONFIG is set to all default settings#
I'm sure it's probably something stupid, probably even a permissions thing somewhere (I've tried executing this as root, fyi), to no avail. Anyone ever experience something similar with Redis?
i have been experiencing redis crashes as well. just an fyi - the guy responsible for much of redis' development, Salvatore Sanfilippo, aka antirez, keeps an interesting blog that has some insight on redis crashes:
http://antirez.com/news/43