10 More Discussions You Might Find Interesting
1. Programming
Hello.
I am new to this forum and I would like to ask for advice about low level POSIX programming.
I have to implement a POSIX compliant C shared library.
A file will have some variables and the shared library will have some functions which need those variables.
There is one special... (5 Replies)
Discussion started by: iamjag
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2. AIX
1.How to know wich process is using the shared memory?
2.How to flush (release) the process from the shared memory? (1 Reply)
Discussion started by: pchangba
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3. UNIX for Advanced & Expert Users
Hi,
Using ipcs we can see shared memory, etc.. details. How can I add/remove shared memory(command name)?
Thanks,
Naga:cool: (2 Replies)
Discussion started by: Nagapandi
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4. Programming
I am writing a shared library in Linux (but compatible with other UNIXes) and I want to allow multiple instances to share a piece of memory -- 1 byte is enough. What's the "best" way to do this? I want to optimize for speed and portability.
Obviously, I'll have to worry about mutual exclusion. (0 Replies)
Discussion started by: otheus
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5. Programming
I need to create a shared library to access an in memory DB. The DB is not huge, but big enough to make it cumbersome to carry around in every single process using the shared library. Luckily, it is pretty static information, so I don't need to worry much about synchronizing the data between... (12 Replies)
Discussion started by: DreamWarrior
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6. Programming
hi,
this is the problem: i want to swap a linked list between 4 processes (unrelated), is there any way i can do that just by sending a pointer to a structure?
//example
typedef struct node
{
int x;
char c;
struct node *next;
} node;
or i should send the items ( x,c ) by... (9 Replies)
Discussion started by: elzalem
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7. Programming
what i want to do is have an int that can been written into by 2 processes but my code doesn't seem to work.
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>
#include<stdio.h>
#define KEY1 (1492)
int main()
{
int shmid;
volatile int * addr;... (6 Replies)
Discussion started by: ddx08
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8. AIX
Hi All,
I'm facing the following issue with my shared libraries in AIX.
memory related calls such as memset, memcpy, malloc etc are failing miserably.
there is something wrong with stack/memory which i can't guess.
i've used the following flags to build my libraray:
ld -G... (0 Replies)
Discussion started by: abhinav05252
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9. HP-UX
Hi, there
On HP-UX, there is a problem about shared memory. The code open the data file and use the "mmap" system call to map into the shared memory, when the contents are make changes, there is no effective on shared memory. The codes look like the following:
...... (0 Replies)
Discussion started by: Frank2004
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10. UNIX for Advanced & Expert Users
I am running HP-UX B.11.11.
I'm increasing a parameter for a database engine so that it uses more memory to buffer the disk drive (to speed up performance). I have over 5GB of memory not being used.
But when I try to start the DB with the increased buffer parameter I get told.
"Not... (1 Reply)
Discussion started by: cjcamaro
1 Replies
pthread_rwlockattr_getpshared(3T) pthread_rwlockattr_getpshared(3T)
NAME
pthread_rwlockattr_getpshared(), pthread_rwlockattr_setpshared() - get or set the process-shared attribute
SYNOPSIS
PARAMETERS
attr Pointer to the read-write lock attributes object whose attributes are to be set/retrieved.
pshared This parameter either specifies the new value of the process-shared attribute (set function) or points to the memory loca-
tion where the process-shared attribute of attr is to be returned (get function).
DESCRIPTION
The attributes object attr must have been previously initialized with the function before these functions are called.
Read-Write locks can be used only by threads within the process or shared by threads in multiple processes. The process-shared attribute in
a read-write lock attributes object describes who may use the read-write lock. The legal values for the process-shared attribute are:
This option permits a read-write lock to be operated upon by any thread
that has access to the memory where the read-write lock is allocated. The application is responsible for allocating the
read-write lock in memory that multiple processes can access.
The read-write lock can only be operated upon by threads created within
the same process as the thread that initialized the read-write lock. If threads of differing processes attempt to operate on
such read-write lock, the behavior is undefined.
The default value of process-shared is
is used to set the process-shared attribute in the initialized attributes object attr. The new value of the process-shared attribute of
attr is set to the value specified in the pshared parameter.
retrieves the value of the process-shared attribute from the read-write lock attributes object attr. The value of the process-shared
attribute of attr is returned in the pshared parameter.
RETURN VALUE
Upon successful completion, and return zero. Otherwise, an error number is returned to indicate the error (the variable is not set).
ERRORS
If any of the following occur, the and functions return the corresponding error number:
is not defined and these functions are not supported.
For each of the following conditions, if the condition is detected, the and functions return the corresponding error number:
The value specified by
attr is invalid.
The value specified by
pshared is not a legal value.
The value pshared points to an illegal address.
WARNINGS
If a read-write lock is created with the process-shared attribute defined as the cooperating processes should have access to the memory in
which the read-write lock is allocated.
AUTHOR
and were developed by X/Open.
SEE ALSO
pthread_create(3T), pthread_rwlockattr_init(3T), pthread_rwlock_init(3T).
STANDARDS CONFORMANCE
Pthread Library pthread_rwlockattr_getpshared(3T)
