Initial Load

Use the C_INIT command arun with the -g option, or the function call hrfexec() to load a restartable process from stable storage into persistent memory. Both arun and hrfexec() provide support for specifying the persistent credentials of a restartable process when the process is initially loaded.

• For a direct process that was run with the arun command, the process name will be system-generated, and the group ID is passed using the -g option. If the group ID is not already in use, a new group is created which contains the direct process. If the group ID already exists, the direct process is added to the corresponding restart group. If no ID is passed after -g, the process is started in the restart group with ID 0.

  A restart group can contain any number of direct processes.

• For an indirect process run with hrfexec(), the process name is specified using a PmmName structure. An indirect process automatically becomes a member of the same process group as the process that spawned it.

Processes that were created directly using acreate(2K) or actorCreate(2K) are not hot restartable and are unable to use the Hot Restart Controller API.

When a process is run as a restartable process, the Hot Restart Controller checks whether a process identified with the specified name is already registered. If this is not the case (as with the initial load), the Hot Restart Controller first solicits the Persistent Memory Manager to allocate the persistent memory blocks which will store the process's process image and executing image. If successful, the Hot Restart Controller registers the name of the new process as a restartable process, running in the specified group.

The subsequent load and start of the persistent process is the same as for a process run using a member of the afexec(2K) function family (see the man page for a description of this process). The only difference is that the process is loaded from its process image (in persistent memory) and not from stable storage.

A restartable process's name remains registered in the Hot Restart Controller for the life of its process group. The lifespan of the group may extend beyond the lifespan of the process. It is the programmer's responsibility to ensure that no two restartable processes will attempt to register with the same name in the Hot Restart Controller.

After a restartable process has been registered and loaded, it runs under the control of the Hot Restart Controller. If the process fails, the failure will invoke the restart of all direct members of its restart group. These direct processes will be responsible for restarting any indirect processes registered in the group. To query a process's restart group, use hrGetprocessGroup(2RESTART):

#include <hr/hr.h>
hrGetprocessGroup(int pid)