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author | Jannis Hoffmann <jannis@fehcom.de> | 2024-07-09 11:44:11 +0200 |
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committer | Jannis Hoffmann <jannis@fehcom.de> | 2024-07-09 11:44:11 +0200 |
commit | f1b71c9fe7dbb4886588a036399cf5ebe16b7c47 (patch) | |
tree | e07786aa479c9fb6ee3e537078470aaab5454f80 /man/qmail-todo.8 | |
parent | a293489ee83c8b05d845a162dc2a4de026f3775d (diff) |
removed top level directory
Diffstat (limited to 'man/qmail-todo.8')
-rw-r--r-- | man/qmail-todo.8 | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/man/qmail-todo.8 b/man/qmail-todo.8 new file mode 100644 index 0000000..740f5b3 --- /dev/null +++ b/man/qmail-todo.8 @@ -0,0 +1,128 @@ +.TH s/qmail: qmail-todo 8 +.SH NAME +qmail-todo \- schedule state change of message for delivery +.SH SYNOPSIS +.B qmail-todo +.SH DESCRIPTION +.B s/qmail +with a high local and remote concurrency number +is able to deliver a tremendous amount of messages (throughput). +Depending on the provided resources however, +often this can not be achieved since +.B qmail-send +becomes a bottleneck on delivery. + +.B qmail-send +preprocesses all new messages before deploying them for +.I local +or for +.I remote +delivering. In a particulur run, +.B qmail-send +does one 'todo' processing, but has the ability to close multiple jobs. +Due to this layout, potentially +.B qmail-send +can not feed all the new available (local/remote) delivery slots +and therefore, it is not possible to achieve the maximum throughput. + +This is a minor problem, given +.B qmail-send +is able to complete this in short time; but due to +many file system calls (fsync and (un)link) a 'todo' +run is expensive and throttles the throughput. + +.B qmail-todo +solves this 'silly qmail (queue) problem' +which is apparent only on system with high injection rates, +delegating the scheduling of 'todo' runs to a dedicated process. + +.SH "COMMUNICATION" +.B qmail-todo +interfaces with +.B qmail-send +on file descriptors \fI[1,8]\fR on sending +and \fI[7,0]\fR for receiving. +.B qmail-todo +communicates with +.B qmail-clean +on file descriptors \fI[2,0]\fR for sending +and \fI[3,1]\fR for receiving. + +.B qmail-todo +and +.B qmail-send +share an extended and peristent message exchange format: + +.EX +D[LRB]<mesgid>\0 + Start delivery for new message with id <messid>. + The character L, R or B defines the type + of delivery: Local, Remote, or Both, respectively. +.EE + +.EX +L<string>\0 + Dump string to the logger without adding additional + '\\n' or similar. +.EE + +.B qmail-todo +sends "\\0" terminated messages, whereas +.B qmail-send +just sends one character to +.BR qmail-todo . + +.SH "BIG PICTURE" +.EX + +-------+ +-------+ + | clean | | clean | + +--0-1--+ +--0-1--+ +-----------+ + trigger ^ | ^ | +->0,1 lspawn | + | | v | v / +-----------+ + +-------+ v +--2-3--+ +--5-6--+ / + | | | | 0<--7 1,2<-+ + | queue |--+--| todo | | send | + | | | | 1-->8 3,4<-+ + +-------+ +-------+ +---0---+ \\ + | \\ +-----------+ + v +->0,1 rspwan | + +---0---+ +-----------+ + | logger| + +-------+ +.EE + +.SH "EXIT CODES" +.B qmail-todo +exits +.I 0 +if the messages have been processed successfully. +It exits +.I 1 +in case there is a communication problem with +.BR qmail-send . +The exit code +.I 111 +together with a diagnostic message is facilitated by +.B qmail-todo +in case it failes reading the required control files. + +.SH "DIAGNOSTICS" +.B qmail-todo +provides additional diagnostic messages to +.B qmail-send +to be displayed in the logs. In particular, in +case of problems creating and (un)linking files. + +.SH "CREDITS" +.B qmail-todo +included in +.B s/qmail +has been created by Andre Oppermann (http://www.nrg4u.com) +as part of this LDAP patch for +.BR qmail . +This man-page uses parts of his EXTERNAL discription. + + +.SH "SEE ALSO" +qmail-send(8), +qmail-queue(8). |