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diff --git a/source/compatibility/v5compatibility.rst b/source/compatibility/v5compatibility.rst new file mode 100644 index 0000000..c7e1865 --- /dev/null +++ b/source/compatibility/v5compatibility.rst @@ -0,0 +1,49 @@ +Compatibility Notes for rsyslog v5 +================================== + +*Written by* `Rainer Gerhards <http://www.gerhards.net/rainer>`_ +*(2009-07-15)* + +The changes introduced in rsyslog v5 are numerous, but not very +intrusive. This document describes things to keep in mind when moving +from v4 to v5. It does not list enhancements nor does it talk about +compatibility concerns introduced by earlier versions (for this, see +their respective compatibility documents). + +HUP processing +-------------- + +The $HUPisRestart directive is supported by some early v5 versions, but +has been removed in 5.1.3 and above. That means that restart-type HUP +processing is no longer available. This processing was redundant and had +a lot a drawbacks. For details, please see the `rsyslog v4 compatibility +notes <v4compatibility.html>`_ which elaborate on the reasons and the +(few) things you may need to change. + +Please note that starting with 5.8.11 HUP will also requery the local +hostname. + +Queue on-disk format +-------------------- + +The queue information file format has been changed. When upgrading from +v4 to v5, make sure that the queue is emptied and no on-disk structure +present. We did not go great length in understanding the old format, as +there was too little demand for that (and it being quite some effort if +done right). + +Queue Worker Thread Shutdown +---------------------------- + +Previous rsyslog versions had the capability to "run" on zero queue +worker if no work was required. This was done to save a very limited +number of resources. However, it came at the price of great complexity. +In v5, we have decided to let a minimum of one worker run all the time. +The additional resource consumption is probably not noticeable at all, +however, this enabled us to do some important code cleanups, resulting +in faster and more reliable code (complex code is hard to maintain and +error-prone). From the regular user's point of view, this change should +be barely noticeable. I am including the note for expert users, who will +notice it in rsyslog debug output and other analysis tools. So it is no +error if each queue in non-direct mode now always runs at least one +worker thread. |