ResourceLimits

ResourceLimits refers to mechanisms that constrain the consumption of system resources by processes, users, or groups. They are used to prevent resource monopolization, improve system stability, and enable predictable performance in multi-tenant environments. Commonly controlled resources include CPU time, memory, file descriptors, disk I/O, and network bandwidth, as well as counts of processes or threads.

In Unix-like systems, resource limits are defined by POSIX RLIMIT settings and enforced by the kernel. Hard limits set the maximum allowed value and soft limits can typically be changed up to the hard limit by the process or its user. Tools such as ulimit or setrlimit adjust these constraints at runtime. Typical limits include CPU time, maximum address space, maximum file size, stack size, number of open files, and number of processes.

Linux extends this concept with cgroups (control groups), which can enforce resource quotas across groups of processes. Cgroups track and limit CPU, memory, I/O, and other resources, and can be nested to reflect hierarchical resource ownership. In modern Linux, cgroup v2 provides unified controllers for simpler management.

In containerized and cloud environments, ResourceLimits often appear as resource requests and limits. Kubernetes, for example, allows per-container CPU and memory limits, along with higher-level constructs like ResourceQuota and LimitRange to constrain usage within a namespace.

From a management perspective, ResourceLimits require careful configuration to balance performance, isolation, and efficiency. Misconfiguration can lead to insufficient resources, throttling, or unintended denials of service.

See also: RLIMIT, ulimit, cgroups, Kernel resource management, Kubernetes resource requests and limits.