Environment variables

Environment variables #

Most tuning lives in pizza.yml (see the configuration file reference) or the runtime settings APIs. The PIZZA_* environment variables below are escape hatches — mostly for benchmarking, diagnostics and crash-safety research; prefer the config file or the settings APIs for anything you want to keep.

Operational knobs #

Variable	Default	Description
`PIZZA_FLUSH_CONCURRENCY`	unset	Overrides `node.flush_concurrency` (1..=16); beats the config file.
`PIZZA_RECOVERY_TAIL_FLUSH`	unset	`0`/`1` forces `wal.local.recovery_tail_flush` off/on, beating the config file.
`PIZZA_RPC_TIMEOUT_SECS`	unset	Deadline for cluster RPC calls (must be > 0).
`PIZZA_COMPACTION_EVERY_TICKS`	unset	Maintenance ticks (500 ms) between background compaction passes.
`PIZZA_COMPACT_TIERS`	unset	Restrict background compaction to specific tier patterns (diagnostics).
`PIZZA_FLUSH_AFTER_IDLE_TICKS`	unset	Idle-tail epoch flush override (same semantics as `wal.local.epoch_flush_after_idle_ticks`).
`PIZZA_SEGMENT_SYNC`	unset	`off` skips the per-segment fsync before WAL purge — the same behavior as `wal.local.segment_durability: async`, without a config change.
`PIZZA_WAL_IO_URING`	unset	Force WAL io_uring on/off (Linux), overriding auto-detection.
`PIZZA_MAX_NODE_BUILDS`	unset	Fallback for the epoch-build concurrency default (`PUT /_node/_local/settings/epoch_build` overrides it at runtime).
`PIZZA_MERGE_POOL_THREADS`	unset	Size of the dedicated compaction merge thread pool.
`PIZZA_ROUTE_CACHE`	unset	Routing-table cache diagnostics/tuning.
`PIZZA_BUILD_BUF_POOL_MB`	unset	Build-buffer pool size in MiB.

Watchdog #

Variable	Default	Description
`PIZZA_RSS_WATCHDOG`	unset	Enable the RSS watchdog (`0` explicitly disables it).
`PIZZA_RSS_SOFT_MB`	60% of MemTotal	Soft RSS threshold (MiB) — sheds load, logs.
`PIZZA_RSS_HARD_MB`	75% of MemTotal	Hard RSS threshold (MiB) — aborts the process.

Diagnostics and profiling #

Off by default; presence enables.

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