Case Study: Canonical restores getent performance with Ubuntu Support

Canonical restores getent performance by eliminating 48,422 repeated disk reads with Ubuntu

Canonical, the company behind Ubuntu, provided support to resolve a critical performance challenge. The customer reported that the standard Linux command 'getent' had become severely slow when enumerating groups using the legacy nssdb backend, making their system with over 24,000 entries effectively unusable for their workload.

Canonical's support engineer traced the issue to a 12-year-old logic bug in the libnss-db code, which was causing 48,422 repeated disk reads during enumeration. The solution involved creating a patch to stop the unnecessary database open-close cycles. By implementing this fix, Canonical restored immediate performance, eliminated the bottleneck, and upstreamed the patch for future Ubuntu releases, demonstrating the value of their deep, code-level support.

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