HP OpenVMS Systems

Ask the Wizard

HP OpenVMS Systems

OpenVMS information

» What's new on our site
» Upcoming events
» Configuration and buying assistance
» Send us your comments

HP OpenVMS systems

» OpenVMS software
» Supported Servers
» OpenVMS virtualization
» OpenVMS solutions and partners
» OpenVMS success stories
» OpenVMS service and support
» OpenVMS resources and information
» OpenVMS documentation
» Education and training

Quick Links

» Non-javascript page
» Ask the Wizard

Test Drive OpenVMS

» OpenVMS I64 test drive
» Java test drive

Other information resources available to you include:

» OpenVMS freeware
» ECO kits, software and hardware support, prior version support
» Alpha SRM, ARC, and AlphaBIOS firmware updates
» ENCOMPASS - HP user group
» OpenVMS software downloads, OpenVMS freeware CD-ROM
» OpenVMS firmware locations
» DECconnect passive adaptor charts
» Cables reference guide
» MicroVAX console commands
» OpenVMS student research

Select a topic below to see Questions Frequently Asked by partners

» Using the online documentation library(installing BNU from the asap SDK)
» Global sections(how to create and use.)
» xx$CREATE_BUFOBJ system service(usage)
» Ethernet address(methods of determination)
» Shareable images(cookbook approach to creating one)
» Sharing data/code at absolute addresses(a guide with examples)
» Determining the Alpha microprocessor
» Using GETSYI to get hardware status

Evolving business value

» Business Systems Evolution
» AlphaServer systems transition planning
» Alpha RetainTrust program

Related links

» HP Integrity servers
» HP Alpha systems
» HP storage
» HP software
» HP products and services
» HP solutions
» HP support
disaster proof
HP Integrity server animation
HP Integrity server animation
Content starts here

Ask the Wizard Questions

What is MUTEX state

The Question is:

I have the following question:

when a system "hangs" you have to force a crash, o.k. no
problem, just corrupt the stack en continue .

Go into SDA and SHOW SUM gives me the process states of the

Several processes are in MUTEX.

Q: What does a MUTEX do and why is my system hanging

I am NOT an expirienced user of SDA, only a system manager .

equipment: microvax 3100-90 VMS 5.5-2

p.s. english is sometimes difficult for a dutchie like me,
so sorry if i have choosen the wrong spelling or words.


The Answer is:

MUTEX is a state that means the process is waiting to own a mutex, which is
a synchronization structure within VMS.  Within SDA look at the Event flag
wait mask in the SHOW PROCESS display.  This should contain the address of
the MUTEX the process is waiting for.  If that address is the same as the
JIB address the the process has run out of either BYTLM or TQELM quota.
You can see which by looking at the JIB$B_FLAGS offset in the JIB.  If it
is a 1 then the process has run out of BYTLM if it is a 2 then the process
has run out of TQELM.  If the Event flag wait mask doesn't point to the JIB
address then the process is waiting on some other MUTEX.  To see which one
use EVAL {Event flag wait mask}.  You may be able to figure out who owns
the MUTEX by looking at the Mutex count field for all processes.  I suggest
you get the book VAX/VMS Internals and Data Structures (ISBN 1-55558-059-9)
as a further source of information on mutexes within OpenVMS.