diff options
| -rw-r--r-- | TAO/docs/leader_follower.html | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/TAO/docs/leader_follower.html b/TAO/docs/leader_follower.html index a5cddb813bd..f722cf12fd3 100644 --- a/TAO/docs/leader_follower.html +++ b/TAO/docs/leader_follower.html @@ -3,40 +3,40 @@ <head> <title>Implementation of leader follower model for global resources</title> </head> - + <BODY text = "#000000" link="#0000ff" vlink="#cc0000" bgcolor="#ffffff"> - + <body> <HR> <h1>Leader follower model for global resources</h1> <HR> <h2>Context</h2> Global resources in TAO mean one ORB and using the reactive strategy - one Reactor. TAO uses the ACE Select Reactor for this purpose. + one Reactor. TAO uses the ACE Select Reactor for this purpose. One main problem with multithreading and only one Reactor is that - only one thread can wait in handle_events at a time. + only one thread can wait in handle_events at a time. Handle_events is called, when a thread expects input, meaning it is blocking to wait for it. - + <h2>Idea</h2> One solution to this problem is to use a leader-follower model, which partitions the set of threads wanting to wait for input into one leader and followers. Every thread is eligible to become a leader. A thread wanting to wait while nobody else is waiting becomes the leader. If the leader gets its input, which is in - this case its response, it will select a new leader out of the + this case its response, it will select a new leader out of the set of followers. The followers wait on a condition variable they own and register it with the ORB core. The ORB core is thereby responsible for making this access thread-save by providing a lock for the list of followers with some flags, like leader_available. - + <h2>Implementation</h2> - The above mentioned condition variables are owned by the - connection handlers, because reponses are expected per connection, + The above mentioned condition variables are owned by the + connection handlers, because responses are expected per connection, not necessarily, thinking about other resource models, per thread. <p> The involved classes are TAO_ORB_Core, TAO_Client_Connection_Handler @@ -44,14 +44,14 @@ a leader reference counter and a leader thread ID were added. The handle_input and send_request methods on the TAO_Client_Connection_Handler contain 95% of the code used for implementing the leader-follower - model. Care has to be taken, that the connection handlers are + model. Care has to be taken, that the connection handlers are suspended and resumed, properly. A special concern is that - no deadlocking occurs. - + no deadlocking occurs. + <HR> For more details and questions, <p> - + <address><a href="mailto:mk1@cs.wustl.edu">Michael Kircher</a></address> <p> <address><a href="mailto:irfan1@cs.wustl.edu">Irfan Pyarali</a></address> |