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11-19-2008 03:32 AM
11-19-2008 03:32 AM
Re: Process mailbox usage simple question
Good, I should read example6 for answer.
I started example6 together with example5 and it just worked.
Anybody wish to know mailboxes and reading this thread, do not make a mistake like me:
1. do not forget about differences between QIO and QIOW;
2. do not forget VMS mailboxes are not a real *mail boxes* and have no cache or buffer. To be able to put anything in immediate mode via QIOW to mailbox you should be sure there is a process that reading from mailbox.
I started example6 together with example5 and it just worked.
Anybody wish to know mailboxes and reading this thread, do not make a mistake like me:
1. do not forget about differences between QIO and QIOW;
2. do not forget VMS mailboxes are not a real *mail boxes* and have no cache or buffer. To be able to put anything in immediate mode via QIOW to mailbox you should be sure there is a process that reading from mailbox.
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11-19-2008 05:38 AM
11-19-2008 05:38 AM
Re: Process mailbox usage simple question
Or use the flags
IO$_WRITEVBLK
IO$M_NOW
IO$M_NORSWAIT
Which our systems have used since the early 90s (and still use).
cheers
Brian
IO$_WRITEVBLK
IO$M_NOW
IO$M_NORSWAIT
Which our systems have used since the early 90s (and still use).
cheers
Brian
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11-19-2008 07:07 AM
11-19-2008 07:07 AM
Re: Process mailbox usage simple question
>1. do not forget about differences between QIO and QIOW;
Asynchronous versus synchronous I/O is a significant difference, yes.
2. do not forget VMS mailboxes are not a real *mail boxes* and have no cache or buffer.
False. OpenVMS mailboxes DO have caching. That's what you set with the quotas.
>To be able to put anything in immediate mode via QIOW to mailbox you should be sure there is a process that reading from mailbox
Actually, you CAN use the synchronous form with an immediate completion flag on the sys$qiow.
OpenVMS is increasingly written in C, which isn't the newest language. Of the older code, that's roughly equally split between Bliss and Macro32.
Both Bliss and C are well-suited to low-level application and OS work, but not without the various and unique weirdness that will be found in each. Both are comparatively old languages.
Read the I/O user's manual, too, while you're reading the manuals. That manual describes how mailboxes work, and it is a good bet that most folks don't understand that.
There are features in mailboxes that I would never recommend using; there are features you think you want to use and that lead to pain and grief. Here are some tips I posted last year: http://64.223.189.234/node/250
Asynchronous versus synchronous I/O is a significant difference, yes.
2. do not forget VMS mailboxes are not a real *mail boxes* and have no cache or buffer.
False. OpenVMS mailboxes DO have caching. That's what you set with the quotas.
>To be able to put anything in immediate mode via QIOW to mailbox you should be sure there is a process that reading from mailbox
Actually, you CAN use the synchronous form with an immediate completion flag on the sys$qiow.
OpenVMS is increasingly written in C, which isn't the newest language. Of the older code, that's roughly equally split between Bliss and Macro32.
Both Bliss and C are well-suited to low-level application and OS work, but not without the various and unique weirdness that will be found in each. Both are comparatively old languages.
Read the I/O user's manual, too, while you're reading the manuals. That manual describes how mailboxes work, and it is a good bet that most folks don't understand that.
There are features in mailboxes that I would never recommend using; there are features you think you want to use and that lead to pain and grief. Here are some tips I posted last year: http://64.223.189.234/node/250
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11-20-2008 04:19 AM
11-20-2008 04:19 AM
Re: Process mailbox usage simple question
I find why example5 is freezing:
IO$M_NOW
should be added to SYS$QIOW() call
to get behavor identical there.
BTW it is mistake in manual ;)
IO$M_NOW
should be added to SYS$QIOW() call
to get behavor identical there.
BTW it is mistake in manual ;)
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