How to Configure Resource Limits with ulimit

How to Configure Resource Limits with ulimit

Resource limits prevent any single process from consuming all available resources on your Breeze. The ulimit command and /etc/security/limits.conf file let you control memory, file descriptors, CPU time, and more.

Viewing Current Limits

# Show all soft limits
ulimit -a

# Show all hard limits
ulimit -Ha

# Show specific limits
ulimit -n    # open files
ulimit -u    # max processes
ulimit -v    # virtual memory (KB)

Setting Temporary Limits

# Increase open file limit for current shell
ulimit -n 65536

# Set max processes
ulimit -u 4096

Persistent Configuration

Edit /etc/security/limits.conf to set permanent limits:

# /etc/security/limits.conf
www-data    soft    nofile    65536
www-data    hard    nofile    65536
deploy      soft    nproc     4096
deploy      hard    nproc     8192
*           soft    core      0

Systemd Service Limits

For services managed by systemd, set limits in the unit file:

# /etc/systemd/system/myapp.service
[Service]
LimitNOFILE=65536
LimitNPROC=4096
LimitCORE=0

sudo systemctl daemon-reload
sudo systemctl restart myapp

Common Limits to Tune

• nofile — open file descriptors (critical for web servers and databases)
• nproc — maximum number of processes per user
• core — core dump file size (set to 0 to disable)
• memlock — locked memory for applications like databases

Properly configured limits keep your Breeze stable under load and prevent runaway processes from causing outages.