Server_Max_Concurrent_Trans

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Description

• Controls how many physical server threads may run a client transaction concurrently.

• By default 20 threads — all further threads wait until one of the running 20 finishes (an artificial bottleneck originally meant to prevent overload).

• Only effective for NRPC connections to the server task. HTTP/IMAP/Router etc. have their own tuning parameters.

• Interplay with Server_Pool_Tasks: per NRPC port, a pool of Server_Pool_Tasks threads is created (default 40). With three NRPC ports, for example, this yields 120 worker threads. So that all can work freely, Server_Max_Concurrent_Trans should be set to the total number of worker threads.

• Default relationship per HCL Wiki: Server_Pool_Tasks = Server_Max_Concurrent_Trans × 2.

Example

Server_Pool_Tasks=40
Server_Max_Concurrent_Trans=120

• Three NRPC ports × 40 threads each → 120 worker threads in total; MaxConcurrentTrans=120 lets all work in parallel.

Server_Max_Concurrent_Trans=20

• HCL default; only 20 NRPC transactions are served concurrently.

Notes

• Sensible only on larger servers with sufficient CPU/RAM. On small systems, raising the value can destabilize the server.

• Changes require a server restart.

• On modern multi-core servers, the historical bottleneck above 20 threads is often considered too restrictive — HCL tuning recommendations therefore tie the value to Server_Pool_Tasks and the number of NRPC ports.

• Works on all supported platforms.

Sources (HCL Product Documentation)

• HCL Software Customer Support – KB0032882 „Server_Max_Concurrent_Trans notes.ini parameter usage“: support.hcl-software.com/csm?id=kb_article&sysparm_article=KB0032882

• HCL Software Customer Support – KB0037705 „How to set the NRPC thread pool size for each Notes port in Domino“: support.hcl-software.com/csm?id=kb_article&sysparm_article=KB0037705

• HCL Notes and Domino Wiki – „Domino Server performance troubleshooting best practices“ (CPU · Server_Max_Concurrent_Trans · Server_Pool_Tasks): ds-infolib.hcltechsw.com/ldd/dominowiki.nsf/dx/Domino_Server_performance_troubleshooting_best_practices

• HCL Domino 14.5.1 – Configuration Settings · NOTES.INI Settings tab (general setting): help.hcl-software.com/domino/14.5.1/admin/othr_configurationsettingsnotesinisettingstab_t.html