eXtremeDB -- the shared memory 80error

The customers got the shared memory 80error on AIX environment; utility truss is used to track the debug info,eXtremeDB.registry access error is found.  Release notesdescribed as follows: These names are constructed using the memory segment'snames and the database name.  eXtremeDB creates these name-files in the user'shome directory with the following naming scheme.

 

 

         kwrite(1," S o c k e t   d o m a i"..,43)     = 43

   Node 20.0.7.5, rank 21234

kwrite(1, "         N o d e   2 0 .".., 30)     = 30

   Node 20.0.7.6, rank 21234

kwrite(1, "         N o d e   2 0 .".., 30)     = 30

   Node 20.0.8.5, rank 21234

kwrite(1, "         N o d e   2 0 .".., 30)     = 30

   Node 20.0.8.6, rank 21234

kwrite(1, "         N o d e   2 0 .".., 30)     = 30

kopen("/app/eXtremeDB_registry",O_WRONLY|O_CREAT|O_TRUNC, ) Err#13 EACCES

statx("/app/eXtremeDB_registry",0x0FFFFFFFFFFFECA0, 176, 010) Err#2 ENOENT

kopen("/app/eXtremeDB_registry",O_WRONLY|O_CREAT|O_TRUNC, ) Err#13 EACCES

statx("/app/eXtremeDB_registry",0x0FFFFFFFFFFFECB0, 176, 010) Err#2 ENOENT

kopen("/usr/share/lib/zoneinfo//Asia/Shanghai",O_RDONLY) = 3

kread(3, " T Z i f2\0\0\0\0\0\0\0".., 41448)   = 405

close(3)                                        = 0

__libc_sbrk(0x0000000000010020)                 = 0x000000011002EFE0

kopen("/usr/share/lib/zoneinfo//posixrules",O_RDONLY) Err#2  ENOENT

kopen("/app/eXtremeDB_registry",O_WRONLY|O_CREAT|O_TRUNC, ) Err#13 EACCES

statx("/app/eXtremeDB_registry",0x0FFFFFFFFFFFEBF0, 176, 010) Err#2 ENOENT

kopen("/app/eXtremeDB_registry",O_WRONLY|O_CREAT|O_TRUNC, ) Err#13 EACCES

statx("/app/eXtremeDB_registry",0x0FFFFFFFFFFFEC00, 176, 010) Err#2 ENOENT

_nsleep(0x0FFFFFFFFFFFEEE0,0x0FFFFFFFFFFFEFB0) = 0

        connecting rc=80        createbefore rc=80Database and memory alloc in 1 msecs

kwrite(1, "\t   c o n n e c t i n g".., 76)     = 76

 

kwrite(1, "\n", 1)                              = 1

       Error connecting database :

       Return Code kwrite(1, "\t E r r o r   c o n n e".., 43) = 43

80: MCO_E_SHM_ERROR - Failed tocreate/attach to shared memory

kwrite(1, " 8 0 :   M C O _ E _ S H".., 63)     = 63

kopen("/app/eXtremeDB_registry",O_WRONLY|O_CREAT|O_TRUNC, ) Err#13 EACCES

statx("/app/eXtremeDB_registry",0x0FFFFFFFFFFFECA0, 176, 010) Err#2 ENOENT

kopen("/app/eXtremeDB_registry",O_WRONLY|O_CREAT|O_TRUNC, ) Err#13 EACCES

statx("/app/eXtremeDB_registry",0x0FFFFFFFFFFFECB0, 176, 010) Err#2 ENOENT

kfcntl(1, F_GETFL, 0x00000000150B0293)          = 67110914

kfcntl(2, F_GETFL, 0x00000000150B0293)          = 67110914

_exit(1)

$

Question: How could we change customize the paththrough eXtremeDB to the currende eXtremeDB directory.

Answer: 

On linux (and most other Unix-es) when using a shared memory database, eXtremeDB uses SysV synchronization primitives and the shared memory API.  Both of these APIs require the names of existing files to identify the sync. primitives and memory segments.  These names are constructed using the memory segment's names and the database name.  eXtremeDB creates these name-files in the user's home directory with the following naming scheme:

“<dbname>.lock” for sync. primitives,

“eXtremeDB.<dbname>” for memory segments,

“eXtremeDB_registry” for the registry.

 

Normally eXtremeDB will remove all these files when the database is closed, but if the program fails it has no chance to do so.  In this case the developer must provide some other means to clear the lock files form this directory.

 

It is possible to change the lock files location by exporting the "EXTREMEDB_DIR" environment variable to setup the path instead of the home directory by entering a command line like one of the following to run a program called “sample”:

 

“export EXTREMEDB_DIR=c:/tmp ./sample”

 

to keep the directory path setting only for the duration of the program execution, or

 

“export EXTREMEDB_DIR=c:/tmp”

 “./sample”

 

to keep the directory path setting active until the next “export” command.