Changeset 23530 for trunk/Ohana/src/opihi/pantasks/notes.txt

Timestamp:

Mar 25, 2009, 11:56:09 AM (17 years ago)

Author:

eugene

Message:

upgrade threading/locking model for pantasks: changes merged from eam_branch_20090322

File:

• trunk/Ohana/src/opihi/pantasks/notes.txt (modified) (1 diff)

trunk/Ohana/src/opihi/pantasks/notes.txt

@@ +1 @@
+
+stdout_cntl:
+  GetJobOutout
+    CheckControllerJob
+      CheckController
+        controller_threads (controlThread)
+  StartController
+  ControllerCommand
+    CheckController
+      controller_threads (controlThread)
+    controller_check (clientThread)
+    controller_host (clientThread)
+    controller_jobstack (clientThread)
+    controller_run (clientThread)
+    controller_status (clientThread)
+    controller_verbose (clientThread)
+    DeleteControllerJob
+      CheckControllerJob
+        CheckController
+          controller_threads (controlThread)
+    CheckControllerJobStatus
+      CheckControllerJob
+        CheckController
+          controller_threads (controlThread)
+    SubmitControllerJob
+      SubmitJob
+        CheckTasks (JobTaskThread)
+    PrintControllerBusyJobs
+    KillControllerJob
+    QuitController
+    RestartController    
+  CheckControllerOutput
+    controller_output (clientThread)
+    controller_threads (controlThread)
+
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+20090322
+
+  We've been surviving with a slightly broken threading / locking
+  model.  I would like to clean it up.  Previously, the threads where
+  blocking at a very coarse level, and there were certain interactions
+  that were not thread-safe.  Here are my notes on re-working this:
+
+  * we have 6 threads:
+
+    * main (top-level parent) : after it spawns the 5 child threads,
+      this thread waits for new clients and adds them to the list of
+      active clients with 'AddNewClient'
+
+    * clientsThread (ListenClients): this thread is listening for
+      commands from the clients; when it receives a complete command,
+      it executes the command using 'multicommand'.
+
+    * tasksThread
+      CheckTasks
+        NextTask
+
+
+
+    * jobsThread
+
+    * controllerThread
+      CheckControllerStatus : race condition is irrelevant
+
+    * inputsThread
+      AddNewInput called by clientThread
+      (not sure this is really being used: 
+           server input (filename) calls 'input'
+           server module (filename) calls 'module'
+
+  * functions which need to be thread-safe:
+    * AddNewClient
+    * gprint and supporting functions must be thread safe (extensively
+      used...)
+
+
+* race condition is irrelevant for this variable
+static int ControllerStatus = FALSE;
+
+static int stdin_cntl, stdout_cntl, stderr_cntl;
+GetJobOutput -> CheckControllerJob -> CheckController -> controllerThread
+ControllerCommand -> controllerThread / clientThread
+CheckControllerOutput -> controllerThread / clientThread
+StartController -> controllerThread / clientThread
+StopController
+
+
+
+static IOBuffer stdout_buffer;
+static IOBuffer stderr_buffer;
+static int ControllerPID = 0;
+
+/* local static variables to track the controller host properties */
+static Host *hosts = NULL;
+static int Nhosts = 0;
+static int NHOSTS = 0;
+
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 PanTasks Client / Server design