Category: Wait Types

The remaining one-API preemptive waits do not warrant a page each, so this reference covers them together. All share the standard mechanics: the thread runs under Windows control (state RUNNING) until the call returns, and the wait measures that external time. Are They a Problem? None has been a noticeable contention point. They exist so…

Four preemptive waits track Windows networking APIs, and this page covers them together: Together they are the OS-call basement under SQL Server’s outbound and transport networking. Are They a Problem? At trace levels, no. The member with the sharpest teeth is GETADDRINFO: slow or flaky DNS makes every outbound name resolution stall, which surfaces as…

PREEMPTIVE_OS_PIPEOPS is recorded when a thread calls out to Windows functions that work with pipes, and in DBA reality that means one thing almost every time: xp_cmdshell. SQL Server launches the external command and reads its output through a pipe; the entire runtime of that command accumulates under this wait. The PREEMPTIVE_ prefix means the…

PREEMPTIVE_OS_QUERYREGISTRY is a generic wait for threads calling Windows registry functions. SQL Server consults the registry for assorted configuration (service settings, network configuration, some feature lookups), and xp_regread and friends route here too. The thread runs preemptively until the registry call returns. Normally a background triviality, with one version-specific exception worth knowing. Is It a…

PREEMPTIVE_OS_REPORTEVENT is recorded when a thread calls the Windows ReportEvent function, writing an entry to the Windows event log. SQL Server mirrors significant error log messages to the Application event log, and features like RAISERROR … WITH LOG, failing logins (when auditing is on), and alert-generating errors all route through this call. Its accumulation is…

Windows authentication and authorization involve a parade of security APIs, and SQL Server has a preemptive wait for each. This page covers the family: PREEMPTIVE_OS_ACCEPTSECURITYCONTEXT, ACQUIRECREDENTIALSHANDLE, AUTHORIZATIONOPS, AUTHZGETINFORMATIONFROMCONTEXT, AUTHZINITIALIZECONTEXTFROMSID, AUTHZINITIALIZERESOURCEMANAGER, COMPLETEAUTHTOKEN, DECRYPTMESSAGE, ENCRYPTMESSAGE, DELETESECURITYCONTEXT, FREECREDENTIALSHANDLE, INITIALIZESECURITYCONTEXT, QUERYCONTEXTATTRIBUTES, QUERYSECURITYCONTEXTTOKEN, REVERTTOSELF, SECURITYOPS, SETNAMEDSECURITYINFO, NETVALIDATEPASSWORDPOLICY, and NETVALIDATEPASSWORDPOLICYFREE. The SSPI negotiation members (ACCEPTSECURITYCONTEXT, INITIALIZESECURITYCONTEXT, COMPLETEAUTHTOKEN) fire on every Kerberos/NTLM…

PREEMPTIVE_OS_WAITFORSINGLEOBJECT is recorded when a thread calls the Windows WaitForSingleObject function to synchronise with an external client process communicating through that kernel object. In practice it is commonly seen together with ASYNC_NETWORK_IO, depending on the network transport in use between SQL Server and its clients: the same slow-consumer condition can express itself through either wait.…

PREEMPTIVE_SB_STOPENDPOINT is recorded when a thread calls out to Windows while shutting down a Service Broker endpoint, the network listener that lets Broker exchange messages between instances. Stopping an endpoint involves OS-level teardown of its networking, done preemptively. Endpoint stops happen at instance shutdown and when someone alters or drops the endpoint, so occurrences are…

PREEMPTIVE_SP_SERVER_DIAGNOSTICS is recorded when the background health-monitor thread is actually running the sp_server_diagnostics procedure, the component-by-component health check added in SQL Server 2012 that feeds AG and FCI failure detection. Its sibling SP_SERVER_DIAGNOSTICS_SLEEP covers the same thread between runs; this preemptive wait covers the runs themselves. Between the two, the health monitor’s entire life is…

Five preemptive waits cover Extended Events session lifecycle operations, and this page covers the set: They meter the administrative edges of Extended Events rather than event capture itself. Are They a Problem? No; none has been a contention point, and their occurrences map to session lifecycle events and target inspections: someone started or stopped a…