Start/notes.ini Parameters/Server_Pool_Tasks

Server_Pool_Tasks

Parameter: Server_Pool_Tasks
Short description: Sets the size of the NRPC worker thread pool per Notes port. Default: 40 threads per port. Scales the number of concurrent NRPC requests the server task can handle. Together with Server_Max_Concurrent_Trans it controls the thread-pool behavior.

Profile

Parameter
Server_Pool_Tasks
Category
Performance (NRPC threading)
Component
Server (server task / NRPC listener)
Available since
8.5
Supported versions
9.0.1, 10.0, 11.0, 12.0, 14.0, 14.5, 14.5.1
GUI equivalent
notes.ini only (no GUI)
Possible values
Integer ≥ 20. Default: 40 (per active Notes port). Typical increase: 60–100.

Description

Server_Pool_Tasks and Server_Max_Concurrent_Trans jointly control the thread-pool behavior of the NRPC layer — i.e. nserver.exe (Windows) or server (Unix). Other tasks (HTTP, IMAP, Router, LDAP) are not affected.
How the pool works:
  • Domino creates a separate worker thread pool per Notes port. So if three Notes ports are operated (e.g. TCPIP, ClusterPort, Spare), three independent pools are created with Server_Pool_Tasks threads each.
  • With default 40 + three ports, that means 120 worker threads plus overhead threads.
  • Worker threads handle NRPC transactions (database reads, view queries, indexer requests from clients, replication responses to other servers).
When to increase?
  • Very many simultaneous Notes clients (≥ several hundred active users).
  • High RPC load through add-ons / backend apps making many small calls.
  • Hub servers receiving many replication connections at the same time.
Symptoms of a bottleneck:
  • show stat Server.Trans.Total and Server.Trans.PerMinute show high load while Server.Trans.Queue.Length and Server.Trans.Queue.MaxLen become unusually high.
  • Users report “hourglass” pauses, mail databases open with delay.
  • The console command show stat Server.Pools.* (where available) shows exhausted thread pools.
Mind the per-port limit: Domino does not allow different pool sizes per Notes port (as of 11/12/14). If you set Server_Pool_Tasks=80, you get 80 on every active port.
Relationship with Server_Max_Concurrent_Trans: the latter limits parallel active transactions. Default Server_Max_Concurrent_Trans=20. For heavily parallelized servers, raise both together, e.g. Server_Pool_Tasks=80 + Server_Max_Concurrent_Trans=40.

Example configuration

Large multi-port server:
Server_Pool_Tasks=60
Server_Max_Concurrent_Trans=30
Very heavily used hub:
Server_Pool_Tasks=100
Server_Max_Concurrent_Trans=40

Notes & pitfalls

  • Server restart required: the thread pool is created at server start. set config Server_Pool_Tasks=… at runtime only changes the notes.ini, not the running pool.
  • RAM requirement: every thread holds its own stack allocation (typically 1–2 MB). With Server_Pool_Tasks=100 × 3 ports, that means roughly 300–600 MB additional working set.
  • Find the sweet spot: too many threads cause context-switching overhead and can degrade performance. Increase gradually (40 → 60 → 80 → 100) and compare statistics.
  • Do not confuse with Replicators: Replicators scales separate replicator tasks, Server_Pool_Tasks scales NRPC worker threads.
  • Mind per-port multiplication: on servers with many Notes ports (e.g. additional ClusterPort), the value multiplies with the number of ports.
  • Monitoring: show stat Server.Trans.*, show stat Server.Pools.* (where available), show server and platform tools (Performance Monitor / top / pidstat).
  • Works on all supported platforms.

Sources (HCL Product Documentation)

  • HCL Support Knowledge Base KB0032882 – relationship between Server_Max_Concurrent_Trans and Server_Pool_Tasks
  • HCL Support Knowledge Base KB0037705 – Server_Pool_Tasks default 40 per Notes port
  • Note: there is no dedicated entry for this parameter in the official help.hcl-software.com/domino/ doc trunk; best-practice recommendations come exclusively from the HCL Support Knowledge Base.