Set up split mirai daemon pools for distributed execution.

Two pools instead of one: read daemons execute source/warp read tasks (and any kernels the placement pass fuses onto them), while compute daemons run the materialised XLA stages. The resource model is: pool width is slots, admission is concurrency. Every daemon is pinned to a disjoint slice of the machine at creation (garry_opt("pool_affinity")), so an XLA client created anywhere is narrow rather than all-cores; the scheduler's live-RAM byte budgets decide how many tasks are actually in flight; excess daemons idle lean. Called with no arguments it sizes the pools to the machine: read = all logical cores (remote fetch is latency-bound, so a wide read pool keeps the network drain full) and compute = a third of the logical cores, capped at 8 with a floor of 2; on CUDA the compute pool is 2, since concurrent clients share one card. collect(distributed = TRUE) detects the pools automatically and pre-compiles stage kernels at run start (garry_opt("jit_warmup")), scan kernels included, targeted at the garry_opt("scan_profiles") designated profiles only.

Usage

garry_daemons(
  read = NULL,
  compute = NULL,
  read_handles = NULL,
  gdal_config = TRUE,
  ...
)

Arguments

read

Read-pool daemon count; NULL (default) uses all logical cores. 0 tears the pool down.

compute

Compute-pool daemon count; NULL (default) uses a third of the logical cores, capped at 8 with a floor of 2 (2 on CUDA: concurrent clients share one card). The compute pool's residual workloads (scans, big fused reductions) are compile-bound: every daemon that runs a scan task pays its kernel compile, so width multiplies compiles without adding admitted concurrency. Larger pools are SAFE at any width (per-daemon affinity masks and byte admission) and pay off for fleets of independent non-fusable tasks; they are an explicit choice, not the default. 0 tears down.

read_handles

Open-handle cache depth on read daemons. NULL (default) uses garry_opt("read_handles"). Depth 1 suits per-slice mosaics that are rarely revisited (every open warped mosaic pins warper and connection memory); plans revisiting a few local multi-band files across many windows want a depth covering the interleaved file count, since closing a dataset discards its GDAL block cache.

gdal_config

Apply garry_gdal_config() on the host and read daemons (default TRUE). Set FALSE to leave session GDAL config untouched (e.g. when mixing local multi-file reads).

...

Passed to mirai::daemons() for both pools.

Value

Invisibly, list(read =, compute =).

Details

You should not need to tune these. The cases for overriding: a source API that throttles concurrent reads (smaller read); one daemon per device on multi-GPU, or one per socket on NUMA (compute); a memory-tight box (smaller compute, each daemon's base XLA client is ~300 MB once warmed).

It also applies the sensible defaults so a workload script needs no preamble: the glibc MALLOC_* thresholds are exported BEFORE the daemons spawn (read at exec, so children inherit them), and garry_gdal_config() runs on every read daemon. Neither touches the host's own GDAL config (that would hide local sidecars for the caller's reads); call garry_gdal_config() yourself to tune host-side discovery. MALLOC_* is only-if-unset, and gdal_config = FALSE skips the GDAL settings entirely.

See also

garry_daemons_set(), garry_pool_hygiene(), collect()