Who spawns a dedicated server process?

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  • Michael J. Moore
    #1

    Who spawns a dedicated server process?

    Is it the listener process, or some other Oracle process. Also, on a UNIX
    system, when you do "ps -ef" to see your processes, the PPID points back to
    a process named "init". Why does the PPID not point to some other process
    like, for example, the listener, or PMON, or whoever spawned it.
    thanks,
    Mike


    Tags: None
    • Ed prochak
      #2
      Re: Who spawns a dedicated server process?

      "Michael J. Moore" <NOhicamelSPAM@ comcast.netwrot e in message news:<UNrcb.425 915$Oz4.221120@ rwcrnsc54>...
      Is it the listener process, or some other Oracle process. Also, on a UNIX
      system, when you do "ps -ef" to see your processes, the PPID points back to
      a process named "init". Why does the PPID not point to some other process
      like, for example, the listener, or PMON, or whoever spawned it.
      thanks,
      Mike
      The processes are spawned by the OS, repesented by the process called
      init. Talk to you UNIX admin about how this works.

      Then my question back to you arises: why do you care?

      If you are the DBA, then you need to hit the manuals some more.
      If you are not the DBA, you should not care.

      (I suspect ayou are not the DBA but you feel to need to control this
      process somehow. If you have some problem of performance or other,
      post that and suggestions will come. Looking at process IDs will get
      you nowhere in understanding the ORACLE operations and architecture.)

      HTH,
      ed

      --
      Magic Interface, Ltd.
      440-498-3700

        Comment

        • Michael J. Moore
          #3
          Re: Who spawns a dedicated server process?

          I have hit the manuals resulting in the very need to ask this question.

          According to OCP 9i Database Fundamentals 1 Exam Guide:

          On page 12 it says: "... the listener tells Oracle to generate a new
          dedicated server ..." yet on page 14 in the questions and answers section it
          says "The listener spawns a new server process."

          So, which is it, "listener tell Oracle" or "listener spawns"? Or now you
          have given me a third option "The processes are spawned by the OS".

          The reason I care is because I would like to be able to answer this question
          correctly if it occurs on an exam.

          regards,

          Mike

          "Ed prochak" <ed.prochak@mag icinterface.com wrote in message
          news:4b5394b2.0 309250457.7c910 5c6@posting.goo gle.com...
          "Michael J. Moore" <NOhicamelSPAM@ comcast.netwrot e in message
          news:<UNrcb.425 915$Oz4.221120@ rwcrnsc54>...
          Is it the listener process, or some other Oracle process. Also, on a
          UNIX
          system, when you do "ps -ef" to see your processes, the PPID points back
          to
          a process named "init". Why does the PPID not point to some other
          process
          like, for example, the listener, or PMON, or whoever spawned it.
          thanks,
          Mike
          >
          The processes are spawned by the OS, repesented by the process called
          init. Talk to you UNIX admin about how this works.
          >
          Then my question back to you arises: why do you care?
          >
          If you are the DBA, then you need to hit the manuals some more.
          If you are not the DBA, you should not care.
          >
          (I suspect ayou are not the DBA but you feel to need to control this
          process somehow. If you have some problem of performance or other,
          post that and suggestions will come. Looking at process IDs will get
          you nowhere in understanding the ORACLE operations and architecture.)
          >
          HTH,
          ed
          >
          --
          Magic Interface, Ltd.
          440-498-3700

            Comment

            • Mr. DB
              #4
              Re: Who spawns a dedicated server process?

              "Michael J. Moore" <NOhicamelSPAM@ comcast.netwrot e in message news:<ypMcb.432 226$cF.134811@r wcrnsc53>...
              I have hit the manuals resulting in the very need to ask this question.
              >
              According to OCP 9i Database Fundamentals 1 Exam Guide:
              >
              On page 12 it says: "... the listener tells Oracle to generate a new
              dedicated server ..." yet on page 14 in the questions and answers section it
              says "The listener spawns a new server process."
              >
              So, which is it, "listener tell Oracle" or "listener spawns"? Or now you
              have given me a third option "The processes are spawned by the OS".
              >
              The reason I care is because I would like to be able to answer this question
              correctly if it occurs on an exam.
              >
              regards,
              >
              Mike
              >
              "Ed prochak" <ed.prochak@mag icinterface.com wrote in message
              news:4b5394b2.0 309250457.7c910 5c6@posting.goo gle.com...
              "Michael J. Moore" <NOhicamelSPAM@ comcast.netwrot e in message
              news:<UNrcb.425 915$Oz4.221120@ rwcrnsc54>...
              Is it the listener process, or some other Oracle process. Also, on a
              UNIX
              system, when you do "ps -ef" to see your processes, the PPID points back
              to
              a process named "init". Why does the PPID not point to some other
              process
              like, for example, the listener, or PMON, or whoever spawned it.
              thanks,
              Mike
              The processes are spawned by the OS, repesented by the process called
              init. Talk to you UNIX admin about how this works.

              Then my question back to you arises: why do you care?

              If you are the DBA, then you need to hit the manuals some more.
              If you are not the DBA, you should not care.

              (I suspect ayou are not the DBA but you feel to need to control this
              process somehow. If you have some problem of performance or other,
              post that and suggestions will come. Looking at process IDs will get
              you nowhere in understanding the ORACLE operations and architecture.)

              HTH,
              ed

              --
              Magic Interface, Ltd.
              440-498-3700
              The last response was not correct. The O/S doesn't know how to start
              Oracle processes on it's own. The ppid of the dedicated server
              processes is the init process because Oracle pulls a little trick to
              make that happen.

              For remote connections (i.e. over the network) the dedicated server
              process is actually spawned by the listener, and Oracle then makes the
              init process into the parent of that dedicated server. If the ppid
              (parent process id) remained the listener, you'd never be able to
              shutdown the listener without killing all of your users. The init
              process didn't start the server process because it doesn't even know
              how to start an Oracle process.

              For local connections (i.e. on the same box, on UNIX), the dedicated
              server process is actually spawned by the client process. You can
              easily see this becaue the ppid of the dedicated server process is the
              client. If I remember correctly, Oracle doesn't make the server
              process into a child of the init process because death of the client
              means the server should die.

              Corrections or comments are welcome...

                Comment

                • Mr. DB
                  #5
                  Re: Who spawns a dedicated server process?

                  "Michael J. Moore" <NOhicamelSPAM@ comcast.netwrot e in message news:<ypMcb.432 226$cF.134811@r wcrnsc53>...
                  I have hit the manuals resulting in the very need to ask this question.
                  >
                  According to OCP 9i Database Fundamentals 1 Exam Guide:
                  >
                  On page 12 it says: "... the listener tells Oracle to generate a new
                  dedicated server ..." yet on page 14 in the questions and answers section it
                  says "The listener spawns a new server process."
                  >
                  So, which is it, "listener tell Oracle" or "listener spawns"? Or now you
                  have given me a third option "The processes are spawned by the OS".
                  >
                  The reason I care is because I would like to be able to answer this question
                  correctly if it occurs on an exam.
                  >
                  regards,
                  >
                  Mike
                  >
                  "Ed prochak" <ed.prochak@mag icinterface.com wrote in message
                  news:4b5394b2.0 309250457.7c910 5c6@posting.goo gle.com...
                  "Michael J. Moore" <NOhicamelSPAM@ comcast.netwrot e in message
                  news:<UNrcb.425 915$Oz4.221120@ rwcrnsc54>...
                  Is it the listener process, or some other Oracle process. Also, on a
                  UNIX
                  system, when you do "ps -ef" to see your processes, the PPID points back
                  to
                  a process named "init". Why does the PPID not point to some other
                  process
                  like, for example, the listener, or PMON, or whoever spawned it.
                  thanks,
                  Mike
                  The processes are spawned by the OS, repesented by the process called
                  init. Talk to you UNIX admin about how this works.

                  Then my question back to you arises: why do you care?

                  If you are the DBA, then you need to hit the manuals some more.
                  If you are not the DBA, you should not care.

                  (I suspect ayou are not the DBA but you feel to need to control this
                  process somehow. If you have some problem of performance or other,
                  post that and suggestions will come. Looking at process IDs will get
                  you nowhere in understanding the ORACLE operations and architecture.)

                  HTH,
                  ed

                  --
                  Magic Interface, Ltd.
                  440-498-3700
                  The last response was not correct. The O/S doesn't know how to start
                  Oracle processes on it's own. The ppid of the dedicated server
                  processes is the init process because Oracle pulls a little trick to
                  make that happen.

                  For remote connections (i.e. over the network) the dedicated server
                  process is actually spawned by the listener, and Oracle then makes the
                  init process into the parent of that dedicated server. If the ppid
                  (parent process id) remained the listener, you'd never be able to
                  shutdown the listener without killing all of your users. The init
                  process didn't start the server process because it doesn't even know
                  how to start an Oracle process.

                  For local connections (i.e. on the same box, on UNIX), the dedicated
                  server process is actually spawned by the client process. You can
                  easily see this becaue the ppid of the dedicated server process is the
                  client. If I remember correctly, Oracle doesn't make the server
                  process into a child of the init process because death of the client
                  means the server should die.

                  Corrections or comments are welcome...

                    Comment

                    • Mr. DB
                      #6
                      Re: Who spawns a dedicated server process?

                      "Michael J. Moore" <NOhicamelSPAM@ comcast.netwrot e in message news:<UNrcb.425 915$Oz4.221120@ rwcrnsc54>...
                      Is it the listener process, or some other Oracle process. Also, on a UNIX
                      system, when you do "ps -ef" to see your processes, the PPID points back to
                      a process named "init". Why does the PPID not point to some other process
                      like, for example, the listener, or PMON, or whoever spawned it.
                      thanks,
                      Mike
                      The init process is the "initial" process that was started when the
                      UNIX system was booted. Everything comes after init. In UNIX, if a
                      process dies, then all of it's children die. If the listener was the
                      parent, then you wouldn't be able to bounce the listener without
                      killing all of the sessions. If PMON (or another background process)
                      was the parent of the dedicated servers, then it would have to respond
                      to all of the signals generated by those clients. It would get VERY
                      ugly from a performance perspective. The init process is the parent
                      because the listener MADE it be the parent. Pretty cool. Don't ask
                      me how they do it. They're smarter than me.

                        Comment

                        • Ed prochak
                          #7
                          Re: Who spawns a dedicated server process?

                          misterdb123@yah oo.com (Mr. DB) wrote in message news:<403d6add. 0309271727.7eb9 9fc@posting.goo gle.com>...
                          "Michael J. Moore" <NOhicamelSPAM@ comcast.netwrot e in message news:<UNrcb.425 915$Oz4.221120@ rwcrnsc54>...
                          Is it the listener process, or some other Oracle process. Also, on a UNIX
                          system, when you do "ps -ef" to see your processes, the PPID points back to
                          a process named "init". Why does the PPID not point to some other process
                          like, for example, the listener, or PMON, or whoever spawned it.
                          thanks,
                          Mike
                          >
                          The init process is the "initial" process that was started when the
                          UNIX system was booted. Everything comes after init. In UNIX, if a
                          process dies, then all of it's children die. If the listener was the
                          parent, then you wouldn't be able to bounce the listener without
                          killing all of the sessions. If PMON (or another background process)
                          was the parent of the dedicated servers, then it would have to respond
                          to all of the signals generated by those clients. It would get VERY
                          ugly from a performance perspective. The init process is the parent
                          because the listener MADE it be the parent. Pretty cool. Don't ask
                          me how they do it. They're smarter than me.

                          Because they start it as a background process. From the UNIX prompt
                          you can perform the similar functions using the nohup command. And yes
                          I did leave this out of my other response. My oversight, I responded
                          too quickly without noting all the possibilities.

                          So the way they do it is actually pretty easy (a couple options during
                          the fork()/exec() processing).

                          (So much information, so hard to know how much the reader needs!)

                          Thanks for the assist mr DB.

                          Ed Prochak

                            Comment

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