Threading model

As noted in dataflow chart each user action is processed by separate thread (sync or async depending on function definition). Pantra provides flexible control for threads creation and elimination. Most of logic is configurable.

If short words pantra allocate MIN_TASK_THREADS threads in advance to handle average traffic. After available threads shortage pantra creates new threads until MAX_TASK_THREADS count reached, and after that, when traffic getting low, it kills redundant threads.

It is also takes care about hanged threads and passive sessions.

digraph "Threading flowchart" { node [shape=box]; Start [label="Function call", shape=ellipse]; End [shape=ellipse]; //AllocateThreads [label="Allocate\nSync Threads"]; CheckFType [label="function type?", shape=diamond]; AsyncThread [label="Put to\nasync thread"]; CheckThreads [label="Check threads\navailable?", shape=diamond]; WaitLag [label="Check 3 seconds\npassed?", shape=diamond]; CheckMaxThreads [label="Check max\nthreads count\nreached?", shape=diamond]; Loop [label="Wait 1 second"]; CreateThread [label="Create\nnew thread"]; RunThread [label="Put to\nsync thread"]; Start -> CheckFType; CheckFType -> AsyncThread [label="async"]; AsyncThread -> End; CheckFType -> CheckThreads [label="sync"]; CheckThreads -> WaitLag [label="no"]; CheckThreads -> RunThread [label="yes"]; WaitLag -> Loop [label="no"]; Loop -> CheckThreads; WaitLag -> CheckMaxThreads [label="yes"]; CheckMaxThreads -> CreateThread [label="no"]; CheckMaxThreads -> Loop [label="yes"]; CreateThread -> RunThread; RunThread -> End; ServiceStart [label="Service thread", shape=ellipse]; SelectActiveThread [label="Select running\nthread"]; SelectStoppedThread [label="Select stopped\nthread"]; CreateMinThreads [label="Create some threads"]; CheckLong [label="Check thread\nrunning long?", shape=diamond]; CheckOld [label="Check stopped\nlong time ago?", shape=diamond]; CheckTooMany [label="Threads amount\ntoo many?", shape=diamond]; StopThread [label="Stop thread"]; KillThread [label="Kill thread"]; Wait1Active [label="Wait 1 second"]; Wait1Stopped [label="Wait 1 second"]; ServiceStart -> CreateMinThreads -> SelectActiveThread -> CheckLong; CheckLong -> StopThread [label="yes"]; StopThread -> Wait1Active -> SelectActiveThread; CheckLong -> Wait1Active [label="no"]; CreateMinThreads -> SelectStoppedThread -> CheckOld; CheckOld -> CheckTooMany [label="yes"]; CheckOld -> Wait1Stopped [label="no"]; Wait1Stopped -> SelectStoppedThread; CheckTooMany -> KillThread [label="yes"]; CheckTooMany -> Wait1Stopped [label="no"]; KillThread -> Wait1Stopped; SessionLoop [label="Session loop", shape=ellipse]; CheckSessionTTL [label="Session is passive\nfor a long?"]; Wait5 [label="Wait 5 seconds"]; KillSession [label="Kill session"]; SessionLoop -> CheckSessionTTL; CheckSessionTTL -> KillSession [label="yes"]; CheckSessionTTL -> Wait5 [label="no"]; KillSession -> Wait5 -> SessionLoop; }

See also

Check method source code tasks_controller()