Adjusting User Quotas and Preempting Processes in Linux: NGINX & PostgreSQL
In a typical web application environment, multiple users run processes on a Linux system, utilizing the NGINX web server and the PostgreSQL database server. This article will guide you through adjusting user quotas and preempting processes in such a system, ensuring optimal performance and resource allocation.
User Quotas
User quotas allow system administrators to control the amount of system resources, such as disk space and the number of processes, that a user or group can consume. This is particularly useful in a shared hosting environment where resources need to be distributed fairly among multiple users.
Checking and Adjusting Disk Quotas
To check disk quotas, use the edquota command followed by the user or group name:
sudo edquota -u username
This will open the editor with the user's disk quota settings. Adjust the values as needed, save, and exit the editor.
Checking and Adjusting Process Quotas
To check and adjust process quotas, use the /etc/security/limits.conf file. Add or modify entries for the desired user or group, specifying the soft and hard limits for the number of processes:
# Example
username hard nproc 100
username soft nproc 80
Preempting Processes
Preempting processes involves terminating or renicing (changing the priority) of processes that consume excessive resources. This can be done manually or automatically using tools like renice, pkill, and cgroups.
Manual Preemption
To manually renice a process, use the renice command followed by the new priority and the process ID:
sudo renice -n newpriority -p process_id
To manually terminate a process, use the pkill command followed by the process name:
sudo pkill -f process_name
Automated Preemption
To automatically preempt processes, use the cgroups (control groups) feature in Linux. Create a new cgroup, add processes to it, and set resource limits:
# Create a new cgroup
sudo mkdir /cgroup/processes
sudo nano /cgroup/processes/cg.conf
# Add processes to the cgroup
sudo cgcreate -g processes:/processes -a username
sudo cgexec -g processes:/processes command
NGINX and PostgreSQL Configuration
To optimize the NGINX web server and PostgreSQL database server, adjust their configuration files:
NGINX Configuration
Edit the nginx.conf file and adjust the number of worker processes and worker connections:
worker_processes 4;
events {
worker_connections 1024;
}PostgreSQL Configuration
Edit the postgresql.conf file and adjust the following settings:
max_connections = 100
shared_buffers = 256MB
effective_cache_size = 1GB
work_mem = 64MB
maintenance_work_mem = 128MB
- User quotas help control resource usage by users and groups.
- Preempting processes allows you to manage excessive resource consumption.
- Optimizing NGINX and PostgreSQL configuration files can improve performance.