fup 03/08.question concerning db2 6000 thread support/does db2 support
db2v2.1 aix 4.1, mtype 58H
Does db2 support multiple thread acces out of single process
Does db2 support dce thread??
Continued research again today but still could not find any documentation
on it. Only could find the fact that db2 is support in a dce
environment. At this time I will request support from toronto.
Sandy call and I told him that in my research I found out
that db2 v2 does not use threads even when installed on aix4.1. Faxed
him information gathered via db2help
-- click search
-search for: threads
-select 'All Libraries' option
-- Double click 'Database Agent' from the list
Note Regarding Multi-Threaded Environments
The database manager can take advantage of the multi-threaded capabilities
of the operating system, if the minimum required level of the operating
system (see your Planning Guide) supports threads.
For example, the minimum version of AIX required is Version 3.2.4 which
does not support threads, and therefore DB2 for AIX does not use threads,
even when installed on AIX Version 4.1. The minimum required version of
OS/2, for example, is Version 2.11 which supports threads, and therefore
DB2 for OS/2 will use threads.
If your version of the database manager takes advantage of multi-threaded
operating system capabilities, you can substitute "threads" in place of
"processes" in the remainder of this section.
A unique and independent agent process is assigned to handle the different
requests to use the facilities of the database manager (that is, to access a
database, take a snapshot of an application, or attach to a database manager
instance), whether from a remote or local client. Each agent process operates with
its own private memory and shares the database manager and database global
resources such as the buffer pool with other agents.
An agent process can either be active or idle. Active agents are assigned to a
client and perform work for that client. Idle agents are not performing work on
behalf of any clients and are waiting to be assigned to a client. If no idle agents
exist when a client requires one, a new agent is dynamically created. Creating a
new agent involves a certain amount of overhead and as a result, improved
CONNECT and ATTACH performance can be noticed if there is an idle agent that
can be activated for a client. The number of idle agents will not exceed the value
given by the max_idleagents configuration parameter (see Maximum Number of
Idle Agents (max_idleagents)). When a client disconnects from a database or
detaches from an instance the agent will be:
o Freed and marked as idle, if the maximum number of idle agents has not
o Terminated and its storage freed, if the maximum number of idle agents has
Once the number of agents reaches the value given by the maxagents
configuration parameter (see Maximum Number of Agents (maxagents)), all
subsequent requests that require a new agent are denied until the number of
agents falls below maxagents.
For each database transaction (unit of work) that occurs when the client is
connected to a database, an agent will attempt to obtain permission to process the
transaction, known as a processing token, from the database manager. Only
agents with a token are permitted by the database manager to execute a unit of
work against a database; the number of tokens available is controlled by the
maxcagents configuration parameter (see Maximum Number of Concurrent
Agents (maxcagents)). If a token is not available, the agent will wait until one is
available, at which time the requested unit of work will be processed.
In addition to the database agents, there are other asynchronous activities
performed by the database manager which run as their own process (or thread),
o Database I/O servers (or I/O prefetchers) (see Prefetching Data into the
o Database asynchronous page cleaners (see Managing the Database Buffer
o Database deadlock detectors
o Event monitors
o Communication and IPC listeners
o Table space container rebalancers.
Each of the above processes is initiated by a generic daemon spawner process.
Support Line: fup 03/08.question concerning db2 6000 thread support/does db2 support ITEM: AV6900L
Dated: March 1996 Category: N/A
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