Open System Services Porting Guide (G06.24+, H06.03+)
Table Of Contents
- What’s New in This Manual
- About This Manual
- 1 Introduction to Porting
- 2 The Development Environment
- 3 Useful Porting Tools
- 4 Interoperating Between User Environments
- Purpose of Interoperability
- The OSS User Environment
- OSS Commands for the Guardian User
- Guardian Commands for the UNIX User
- OSS Pathname and Guardian Filename Conversions
- Running the OSS Shell and Commands From TACL
- Running Guardian Commands From the OSS Shell
- Running OSS Processes With Guardian Attributes
- Using OSS Commands to Manage Guardian Objects
- 5 Interoperating Between Programming Environments
- 6 OSS Porting Considerations
- 7 Porting UNIX Applications to the OSS Environment
- 8 Migrating Guardian Applications to the OSS Environment
- General Migration Guidelines
- C Compiler Issues for Guardian Programs
- Using New and Extended Guardian Procedures
- Using OSS Functions in a Guardian Program
- Interoperating With OSS Programs
- Starting an OSS Program From the Guardian Environment
- C Compiler Considerations for OSS Programs
- Porting a Guardian Program to the OSS Environment
- How Arguments Are Passed to the C or C++ Program
- Differences in the Two Run-Time Environments
- Which Run-Time Routines Are Available
- Use of Common Run-Time Environment (CRE) Functions
- Replacing Guardian Procedure Calls With Equivalent OSS Functions
- Which IPC Mechanisms Can Be Used
- Interactions Between Guardian and OSS Functions
- 9 Porting From Specific UNIX Systems
- 10 Native Migration Overview
- 11 Porting or Migrating Sockets Applications
- 12 Porting Threaded Applications
- A Equivalent OSS and UNIX Commands for Guardian Users
- B Equivalent Guardian Commands for OSS and UNIX Users
- C Equivalent Inspect Debugging Commands for dbx Commands
- D Equivalent Native Inspect Debugging Commands for dbx Commands
- E Standard POSIX Threads Functions: Differences Between the Previous and Current Standards
- Glossary
- Index
OSS Porting Considerations
Open System Services Porting Guide—520573-006
6-17
The SIGCHLD Signal and the Creation of Zombie
Processes
°
High interoperability with Guardian processes and subsystems
°
Can be called from either a Guardian or OSS process
°
Creates a process on another processor efficiently, thereby providing load
balancing
°
OSS processes can be persistent when PROCESS_SPAWN_ is used in a
Guardian process pair monitor
°
File opens are not propagated to the child process
•
PROCESS_LAUNCH_ procedure call (supersedes PROCESS_CREATE_)
°
Provides the same services and support as the PROCESS_CREATE_
procedure call
°
Can be called from either a Guardian or OSS process
°
Can be called from native and TNS processes
°
Supports specifying maximum heap and main stack values
•
PROCESS_CREATE_ procedure call (superseded by PROCESS_LAUNCH_)
°
Can create only Guardian processes
°
Creates a process on another processor efficiently, thereby providing load
balancing
°
Can be called from either a Guardian or OSS process
°
Can be called from native and TNS processes
The SIGCHLD Signal and the Creation of
Zombie Processes
In UNIX programs, the SIGCHLD signal is used to notify parent processes of the
termination of child processes. The OSS implementation of the SIGCHLD signal differs
from other implementations of UNIX. The OSS implementation may result in the
creation of zombie processes in certain cases unless specific action is taken to prevent
their creation.
A zombie process is a process that occupies a slot in the process table but has no
other space allocated to it. Zombie processes should be removed in order to free
system resources.
The OSS implementation of SIGCHLD conforms to the POSIX.1 standard (IEEE Std.
1003.1-1990). This implementation allows an application to ignore the SIGCHLD signal
in the event that the application does not want to catch the signal. As required by the
standard, ignoring SIGCHLD is the default action. However, the POSIX.1 standard
does not specify the behavior when SIGCHLD is ignored. In the OSS implementation,
when a child process exits and SIGCHLD is ignored, the child process is transformed