How to fix "another app is currently holding the yum lock" error

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If you are working with Linux environment, you must have once in your carrier ended up with this error "another app is currently holding the yum lock" or "Existing lock /var/run/yum.pid: another copy is running as pid XXX" while executing yum. I mostly use RHEL/CentOS environment in my work life so will only talk about this distribution. But i can say with some confidence that the same steps should work with SuSE environment.

Now this error "another app is currently holding the yum lock" is seen mostly with older yum versions especially with YUMv3 which was part of RHEL/CentOS 6 and also some versions of RHEL/CentOS 7. Now with RHEL 7.7, Red Hat has moved to YUMv4. We will discuss about the change in later part of this article.

For now let's see how you can overcome and fix "another app is currently holding the yum lock" error. For the sake of this article I have manually simulated this error by running two parallel yum sessions on different terminals using RHEL/CentOS 7.

Method 1: Kill the locked process to fix "another app is currently holding the yum lock"

Now it is obvious that another session of yum is in progress which is why your yum session is not allowed to run and is waiting for another one to exit. Now until the other yum process exits, your yum process will continue to throw "another app is currently holding the yum lock" as shown below:

# yum install sntp.x86_64
Loaded plugins: fastestmirror
Existing lock /var/run/yum.pid: another copy is running as pid 9571.
Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: yum
    Memory :  86 M RSS (408 MB VSZ)
    Started: Thu Feb  6 20:44:53 2020 - 00:35 ago
    State  : Sleeping, pid: 9571
Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: yum
    Memory :  86 M RSS (408 MB VSZ)
    Started: Thu Feb  6 20:44:53 2020 - 00:37 ago
    State  : Sleeping, pid: 9571

Now the output itself states the PID of another process which is using /var/run/yum.pid or you can manually view the content of this file to get the PID of other yum process

HINT:

With every execution of yum, it will create /var/run/yum.pid file and add the PID of the process in this file.

# cat /var/run/yum.pid
9571

So we know there is a process with PID "9571" locking yum. To get more details on this process you can use ps. Below command will tell you about the command which is using PID 9571

# ps -p 9571
  PID TTY          TIME CMD
 9571 pts/1    00:00:03 yum

To get more details you can use "ps -ef" as shown below

# ps -ef | grep 9571
root      9571  9498  4 20:44 pts/1    00:00:03 /usr/bin/python /usr/bin/yum install nagios-plugins-ntp.x86_64
root      9576  9477  0 20:46 pts/0    00:00:00 grep --color=auto 9571

So there is another session of yum which is installing nagios-plugins-ntp and hence creating the lock file.

So either you can wait for that process to complete or you can manually kill the process

WARNING:

This is not recommended in production environment as it may leave your Linux node in an unusable state. The recommendation would be to let the other process complete.

# kill -9 9571

Now it is also possible that there are some other process which are using yum such as PackageKit used with RHEL/CentOS 6/7, this may keep the lock for longer period so based on your requirement you can choose to disable this service

To permanently stop and disabling PackageKit On CentOS/RHEL 7

# systemctl disable packagekit --now

To permanently Disabling PackageKit On CentOS/RHEL 6 open below file and change enabled=1 to enabled=0

# vi /etc/yum/pluginconf.d/refresh-packagekit.conf
enabled=0

Method 2: Use DNF instead of YUM

With CentOS/RHEL 7 we have an alternate tool "dnf" as a package manager. You must understand that there are major improvements with dnf and should not be considered same as yum.

So if your yum is throwing "another app is currently holding the yum lock" then you can use dnf as an alternative. But this would require dnf rpm to be installed in your environment which by default will not be installed in RHEL/CentOS 7.

NOTE:

On RHEL system you must have an active subscription to RHN or you can configure a local offline repository using which "yum" package manager can install the provided rpm and it's dependencies.

# yum install dnf

Next in future you can completely switch to dnf but for some reason if someone in your team still uses yum and you get "another app is currently holding the yum lock" error then you can start using dnf package manager.

As you see below, both can run in parallel:

# ps -ef | egrep yum\|dnf | grep -v grep
root      9626  9498  2 20:59 pts/1    00:00:03 /usr/bin/python /usr/bin/yum install nagios-plugins-ntp.x86_64
root      9628  9477 36 21:00 pts/0    00:00:35 /usr/bin/python2 /usr/bin/dnf install sntp.x86_64

YUM vs DNF

Since we are discussing on this topic, Let us do some brief comparison between YUM and DNF

With RHEL/CentOS 8 they have introduced YUMv4

# rpm -q yum
yum-4.2.7-7.el8_1.noarch

Although this will internally be linked with DNFv3.

# ls -l /usr/bin/yum
lrwxrwxrwx 1 root root 5 Dec 19 21:13 /usr/bin/yum -> dnf-3

YUMv4 has the following advantages over the previous YUMv3 used on Red Hat Enterprise Linux 7:

Increased performance
New features available, most significantly the support for managing the modular content
Well-designed stable API for integration with tooling

There are various other changes in DNF compared to YUM

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