diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/make.texi | 87 |
1 files changed, 52 insertions, 35 deletions
diff --git a/doc/make.texi b/doc/make.texi index ea58d6e..5a95f0c 100644 --- a/doc/make.texi +++ b/doc/make.texi @@ -4131,15 +4131,15 @@ running in parallel, they will communicate so that only one of them is generating output at a time. There are four levels of granularity when synchronizing output, -specified by giving an argument to the option (e.g., @samp{-Ojob} or -@samp{--output-sync=make}). +specified by giving an argument to the option (e.g., @samp{-Oline} or +@samp{--output-sync=recurse}). @table @code @item none This is the default: all output is sent directly as it is generated and no synchronization is performed. -@item job +@item line Output from each individual line of the recipe is grouped and printed as soon as that line is complete. If a recipe consists of multiple lines, they may be interspersed with lines from other recipes. @@ -4149,7 +4149,7 @@ Output from the entire recipe for each target is grouped and printed once the target is complete. This is the default if the @code{--output-sync} or @code{-O} option is given with no argument. -@item make +@item recurse Output from each recursive invocation of @code{make} is grouped and printed once the recursive invocation is complete. @@ -4158,25 +4158,50 @@ printed once the recursive invocation is complete. Regardless of the mode chosen, the total build time will be the same. The only difference is in how the output appears. -The @samp{make} mode provides the most comprehensive grouping, -allowing output from all targets built by a given makefile to appear -together. However, there will be long interludes during the build -where no output appears while a recursive @code{make} is running, -followed by a burst of output. This mode is best for builds being -performed in the background, where the output will be examined later. - -The @samp{job} mode is mainly useful for front-ends that may be -watching the output of @code{make} and looking for certain generated -output to determine when recipes are started and completed. - -You should be aware that some programs may act differently when they -determine they're writing output to a terminal versus a file -(typically described as ``interactive'' vs. ``non-interactive'' -modes). If your makefile invokes a program like this then using the -output synchronization options will cause the program to believe it's -running in ``non-interactive'' mode even when it's writing to the -terminal. Of course, invoking @code{make} with output redirected to a -file will elicit the same behavior. +The @samp{target} and @samp{recurse} modes both collect the output of +the entire recipe of a target and display it uninterrupted when the +recipe completes. The difference between them is in how recipes that +contain recursive invocations of @code{make} are treated +(@pxref{Recursion, ,Recursive Use of @code{make}}). For all recipes +which have no recursive lines, the @samp{target} and @samp{recurse} +modes behave identically. + +If the @samp{recurse} mode is chosen, recipes that contain recursive +@code{make} invocations are treated the same as other targets: the +output from the recipe, including the output from the recursive +@code{make}, is saved and printed after the entire recipe is complete. +This ensures output from all the targets built by a given recursive +@code{make} instance are grouped together, which may make the output +easier to understand. However it also leads to long periods of time +during the build where no output is seen, followed by large bursts of +output. If you are not watching the build as it proceeds, but instead +viewing a log of the build after the fact, this may be the best option +for you. + +If you are watching the output, the long gaps of quiet during the +build can be frustrating. The @samp{target} output synchronization +mode detects when @code{make} is going to be invoked recursively, +using the standard methods, and it will not synchronize the output of +those lines. The recursive @code{make} will perform the +synchronization for its targets and the output from each will be +displayed immediately when it completes. Be aware that output from +recursive lines of the recipe are not synchronized (for example if +the recursive line prints a message before running @code{make}, that +message will not be synchronized). + +The @samp{line} mode can be useful for front-ends that are watching +the output of @code{make} to track when recipes are started and +completed. + +Some programs invoked by @code{make} may behave differently if they +determine they're writing output to a terminal versus a file (often +described as ``interactive'' vs. ``non-interactive'' modes). For +example, many programs that can display colorized output often will +not do so if they determine they are not displaying on a terminal. If +your makefile invokes a program like this then using the output +synchronization options will cause the program to believe it's running +in ``non-interactive'' mode even when it's ultimately writing to the +terminal. @node Parallel Input, , Parallel Output, Parallel @subsection Input During Parallel Execution @@ -8702,18 +8727,10 @@ uninterrupted sequence. This option is only useful when using the will be displayed as it is generated by the recipes.@refill With no type or the type @samp{target}, output from the entire recipe -of each target is grouped together. With the type @samp{job}, output -from each job in the recipe is grouped together. With the type -@samp{make}, the output from an entire recursive make is grouped -together. The latter achieves better grouping of output from related -jobs, but causes longer delay since messages do not appear until the -entire recursive make has completed (this does not increase the total -build time, though). In general @samp{target} mode is useful when -watching the output while make runs, and @samp{make} mode is useful -when running a complex parallel build in the background and checking -its output afterwards. The @samp{job} mode may be helpful for tools -which watch the output to determine when recipes have started or -stopped. +of each target is grouped together. With the type @samp{line}, output +from each line in the recipe is grouped together. With the type +@samp{recurse}, the output from an entire recursive make is grouped +together. @xref{Parallel Output, ,Output During Parallel Execution}. @item -q @cindex @code{-q} |