openbsd-ports/infrastructure/man/man1/dpb.1

.\"	$OpenBSD: dpb.1,v 1.49 2012/11/06 08:26:29 espie Exp $
.\"
.\" Copyright (c) 2010 Marc Espie <espie@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: November 6 2012 $
.Dt DPB 1
.Os
.Sh NAME
.Nm dpb
.Nd distributed ports builder
.Sh SYNOPSIS
.Nm dpb
.Bk -words
.Op Fl acemqrRsuUx
.Op Fl A Ar arch
.Op Fl b Ar logfile
.Op Fl C Ar pathlist
.Op Fl D Ar PARAM Ns = Ns Ar value
.Op Fl f Ar m
.Op Fl F Ar m
.Op Fl h Ar hosts
.Op Fl I Ar pathlist
.Op Fl J Ar p
.Op Fl j Ar n
.Op Fl L Ar logdir
.Op Fl M Ar threshold
.Op Fl P Ar pathlist
.Op Fl S Ar sizefile
.Op Ar pathlist ...
.Ek
.Sh DESCRIPTION
.Nm
is used to build ports on a cluster of machines, or on a single machine
with several cores.
Its name is an acronym for
.Sq distributed ports builder .
.Nm
walks the ports tree to figure out dependencies, and starts building
as soon as it can.
.Pp
On a clean machine,
.Nm
will run with sensible defaults if used without options.
Note, however, that it will produce logs, lock files, packages, and package
installations.
.Pp
.Nm
can be restricted to a subset of the tree by giving it
.Ar pathlist ...
to build as parameters.
.Pp
A
.Ar pathlist
is either a
.Xr pkgpath 7
to build, or a filename that contains pkgpaths (one per line).
.Ar pathlist
parameters can also take the form
.Li filename*scale
in order to multiply the weights of all
.Xr pkgpath 7
in a file by a given
.Ar scale ,
or
.Li pkgpath=value ,
in order to set the weight of a given
.Xr pkgpath 7
to a specific value.
.Pp
.Nm
supports
.Sq hot-fixes :
if a particular port errors out, it is possible to fix the problem, remove
the corresponding lockfile, and
.Nm
will pick it up without needing to be stopped and restarted.
.Pp
In order to build on a cluster, the ports tree itself should be shared
through NFS, including distfiles and built packages, but the WRKOBJDIR
should be local to each machine.
Option
.Fl h Ar file
is used to specify hosts to use,
.Ar file
can be as simple as a list of hosts to use, one host per line.
.Pp
As
.Nm
tends to be run on shared clusters, most filenames will go through some
control sequence expansions.
For instance, the default logdir location can be specified as
.Pa %p/logs/%a .
The following sequences are recognized:
.Bl -tag -offset aaaa -width %aa
.It Cm %a
architecture being used.
.It Cm %d
date at start of
.Nm ,
GMtime, formatted as yyyy-mm-dd@hh:mm:ss.
.It Cm %f
fetch distfiles location (DISTDIR).
.It Cm %h
hostname running
.Nm .
.It Cm %p
portsdir location.
.It Cm %t
timestamp (number of seconds since January 1 1970) at start of
.Nm .
.El
.Pp
Options are as follows:
.Bl -tag -width pkgpathlong
.It Fl A Ar arch
Build packages for given architecture, selecting relevant hosts from the
cluster.
By default, the current host's architecture will be used.
.It Fl a
Walk the whole tree and builds all packages (default if no
.Ar pathlist
is given).
.It Fl b Ar logfile
Prime the heuristics module with a previous build log, so that packages that
take a long time to build will happen earlier.
.It Fl c
Clean port working directory and log before each build.
.It Fl C Ar pathlist
Don't clean port working directories after build.
Use a list of simple
.Xr pkgpath 7 ,
as this does not take subpackages and flavors into account.
.It Fl D Ar PARAM Ns = Ns Ar value
Set defined parameter to value.
Known parameters are as follows:
.Bl -tag -width DISP
.It ALWAYS_CLEAN
Set to 1 if
.Nm
should clean work directories even if the port errored out.
.It Ar CDROM_ONLY
Don't fetch distfiles that are not allowed for cdrom.
.It Ar CONNECTION_TIMEOUT
Connection timeout for ssh.
Defaults to 60 seconds.
.It Ar DISPLAY_TIMEOUT
Display timeout (in seconds) while waiting for jobs to finish, so that the
display is updated even if jobs didn't finish.
Defaults to 10 seconds.
.It Ar DONT_BUILD_ONCE
By default,
.Nm
will use the
.Ev BUILD_ONCE
optimization
.Po
see
.Xr bsd.port.mk 5
.Pc
if run with
.Fl a :
pseudo-flavors that disable subpackages and are not necessary for bootstrap
will be disabled, so that the same port is built once, as far as possible.
This flag disables that optimization, which might be desireable if you want
to build a small subset of packages which would pull in the kitchen sink
otherwise.
.It Ar DONT_CLEAN_LOCKS
By default,
.Nm
will clean old locks from dpb running on the same host that no longer exist,
provided they didn't end in error.
This is usually the right thing to do after a crash, or after killing dpb
abruptly.
Sometimes, one may want manual control over which locks to remove.
.It Ar FTP_ONLY
Don't fetch distfiles that are not allowed for ftp.
.It Ar HISTORY_ONLY
Don't fetch or build anything.
Only run
.Nm
to figure out old distfiles and update
.Pa ${FULLDISTDIR}/history .
.It Ar NO_CURSOR
Make the terminal cursor invisible if possible.
Avoids flickering on slow graphics cards.
.It Ar NO_BUILD_STATS
Disable reading/saving of default build stats under
.Pa ${DISTDIR}/build-stats/${ARCH} .
.It Ar STUCK_TIMEOUT
Timeout (in seconds * speed factor) after which tasks that don't show
any progress will be killed.
This can be instead set on a per-core basis as the
.Sq stuck
property.
Note that this will always be divided by the core's speed factor.
.It Ar WAIT_TIMEOUT
Timeout (in seconds) to wait before giving up on NFS packages showing up.
Set to 0 to disable.
Defaults to 10 minutes.
.\" Disabled on localhost.
.El
.It Fl e
The listing job is extra and won't be given back to the pool when it's
finished.
.It Fl f Ar m
Create
.Ar m
jobs for fetching files.
Those are separate from the build jobs, since they don't consume cpu, and they
run on the localhost.
Defaults to 2.
Can be set to 0 to bypass fetching jobs entirely,
and reduce
.Nm
memory footprint by a lot.
.It Fl F Ar m
Fetch-only mode, for mirroring hosts.
Do not build any package but fetch everything, disregarding
.Ev BROKEN
and
.Ev ONLY_FOR_ARCHS
information.
.It Fl h Ar hosts
File with hosts to use for building.
One host per line, plus properties, such as:
.Bd -literal -offset indent
espie@aeryn jobs=4 arch=i386
.Ed
.Pp
The special hostname
.Ar DEFAULT
can be used to preset defaults.
It should be used at the start of the file.
.Pp
Use
.Ar localhost
to specify the local machine.
.Nm
will special-case it and not use
.Xr ssh 1
to connect.
.Pp
Properties are as follows:
.Bl -tag -width memory=150
.It arch=value
Architecture of the concerned host.
(there should be a startup task to check consistency, but
currently this has to be set manually on heterogeneous networks.)
.It always_clean=n
Set to 0 or 1 on per-host basis.
See
.Ar ALWAYS_CLEAN
parameter.
.It jobs=n
Number of jobs to run on that host, defaults to hw.ncpu.
.It junk=n
Junk unused packages each n steps.
See
.Fl J
option.
.It memory=thr
Builds everything below that wrkdir threshold in /tmp, assuming
it is a memory filesystem.
Avoid for now, as
.Xr mfs 8
has serious race conditions which yield
random errors under stress conditions such as bulk build.
.It parallel=p
Run big ports on several cores.
See
.Fl p
option.
.It sf=n
Speed factor.
An estimate of that machine's speed with that number of jobs
compared to other machines in the same network.
Works better with small values, in the range of 1..50.
The machine (or machines) with the highest speed factor will
get access to all jobs, whereas other machines will be clamped
to stuff which does not take too long.
Requires previous build information to be effective.
.It stuck=s
Stuck timeout (in seconds * sf) after which tasks which show no progress
will get killed.
.It timeout=s
Defines a specific connection timeout for ssh to that host.
.El
.Pp
The
.Ar hosts
file can also define a start-up script, as
.Bd -literal -offset indent
STARTUP=path
.Ed
.Pp
which will be run at start-up on each machine.
There are no fine-grained options to control
.Xr ssh 1
options, as those can be specified through virtual host declarations in
.Xr ssh_config 5 .
.It Fl I Ar pathlist
List of
.Xr pkgpath 7
to install, on the local box.
This will also add them to the list of things to build.
.It Fl J Ar p
Override value for the
.Dq junk
property.
Delete unneeded installed packages during the build.
Each
.Ar prepare
stage is followed by a
.Ar show-prepare-results
stage.
Every
.Ar p
build, it will be followed by a
.Ar junk
stage which uses
.Xr pkg_delete 1
with the
.Fl aX
options to delete automatically installed packages that are currently
not needed.
.Pp
.Nm
keeps track of list of dependencies on a given host, by storing each
dependency list in the lockfile corresponding to the package being built.
.Pp
There is a potential race condition between the
.Ar depends
and
.Ar junk
stage, which
.Nm
solves by preventing more than one job on a given host to be in the
.Ar depends
\&...
.Ar junk
stages at one time, by using a per-host lock.
.Pp
Defaults to
.Ar 250 .
Can be disabled by setting to
.Ar 0 .
.It Fl j Ar n
Number of jobs to run on a single host (defaults to hw.ncpu).
.It Fl L Ar logdir
Choose a log directory.
.Po
Defaults to
.Pa ${PORTSDIR}/logs/${ARCH}
.Pc .
.It Fl M Ar threshold
Build ports besides the memory threshold within
.Pa /tmp .
Avoid for now, as
.Xr mfs 8
has serious race conditions which yield
random errors under stress conditions such as bulk build.
.It Fl m
Force tty-style reporting.
.It Fl P Ar pathlist
Read list of
.Xr pkgpath 7
from file.
.It Fl p Ar parallel
Override value for the
.Dq parallel
property.
.Pp
Run big jobs on several cores on the same host, by using
MAKE_JOBS=k .
.Pp
Once such a job has started,
.Nm
will not start new jobs on the same host until the big job has
stolen enough cores from other finishing jobs.
.Pp
Only big ports which are safe for parallel building (annotated with
DPB_PROPERTIES = parallel in their Makefile) will be affected.
.Pp
It is advisable to set k to an integral fraction of the
number of cores available on a given host.
.Ar parameter
can be an integer, or of the form
.Sq /n ,
in which case,
.Nm
will set k to a fraction of the total number of jobs
on the machine, but never below 2.
.Pp
Defaults to
.Sq /2 .
.It Fl q
Don't quit while errors/locks are around.
.It Fl r
Random build order.
Disregard any kind of smart heuristics.
Useful to try to find missing build dependencies.
.It Fl R
Rebuild existing packages based on discrepancies between the package
signature and what the port says it should be.
Concretely, use to run a partial bulk build after some library change.
.Pp
Note that
.Fl R
won't always work, as rebuilding a package when another version is already
installed is not supported.
It will go into an infinite loop with always-update packages such as sqlports
or pkglocatedb.
.It Fl s
Compute workdir sizes before cleaning up, and stash them in log file
.Pa ${LOGDIR}/size.log .
.It Fl S Ar sizefile
Read a size log file and use it for choosing to put WRKDIR in memory.
.It Fl u
Update existing packages during dependency solving.
Can be used to run a bulk-build on a machine with installed packages,
but might break a bit, since some packages only build on a clean machine
right now.
.It Fl U
Insist on updating existing packages during dependency solving,
even if the new package apparently didn't change.
.It Fl x
No tty report, only report really important things, like hosts going down
and coming back up, build errors, or builds not progressing.
.El
.Pp
.Nm
figures out in which order to build things on the fly, and constantly
displays information relative to what's currently building.
There's a list of what is currently running, one line per job.
Those jobs are ordered in strict chronological order, which means that
long running builds will tend to percolate to the top of the list.
Normal jobs look like this:
.Bd -literal -offset indent
www/mozilla-firefox(build) [9452] 41% unchanged for 92 seconds
.Ed
.Pp
This contains:
.Bl -dash
.It
the pkgpath being built,
.It
the step currently being run,
.It
the pid running that task (note that this is always a pid on the host
running dpb: for distributed builds, it will be an
.Xr ssh 1
to another machine),
.It
the current size of the log file (displayed as a percentage if option
.Fl b
has been used),
.It
and a possible notice that things might be stuck when
the log file doesn't change for long periods.
.El
.Pp
And fetch jobs look like this:
.Bd -literal -offset indent
<dist-3.0.tgz(#1) [4321] 25%
.Ed
.Pp
This contains:
.Bl -dash
.It
the file being fetched
.It
the number of the
.Ev MASTER_SITE
being tried
.It
the pid of the
.Xr ftp 1
process (note that fetch jobs are always local).
.It
a progress percentage.
.El
.Pp
This is followed by a summary display:
.Bl -tag -width BB=
.It I=
number of built packages that can be installed.
.It B=
number of built packages, not yet known to be installable,
because of possibly run depends that still need to be built.
.It Q=
number of packages in the queue, e.g., stuff that can be built now, assuming
we have a free slot.
.It T=
number of packages to build, where dependencies are not yet resolved.
.It F=
number of distfiles to fetch, when
.Fl f
is used.
.It !=
number of ignored packages.
Details in
.Pa engine.log .
.It L=
list of packages that cannot currently be built because of locks.
.It E=
list of packages in error, that cannot currently be built.
.El
.Pp
If those two lists are empty, they won't even show up.
Note that those numbers refer to pkgpaths known to
.Nm .
In general, those numbers will be slightly higher than the actual number
of packages being built, since several paths may lead to the same package.
.Pp
.Nm
uses some heuristics to try to maximise the queue as soon as possible.
There are also provisions for a feedback-directed build, where information from
previous builds can be used to try to build long-running jobs first.
.Pp
Similarly, fetches will use the continue option of
.Xr ftp 1 ,
since distfiles are checksummed after the fetch anyways.
.Sh LOCKS AND ERRORS
When building a package,
.Nm
produces a lockfile in the locks directory, whose name is deduced from
the basic pkgpath with slashes replaced by dots.
This lockfile is filled with such info as the build start time or the host,
or the needed dependencies for this pkgpath.
.Pp
The lockfile will also contain the name of a parent pkgpath, for paths that
were discovered as dependencies.
This is particularly useful for bogus paths, where it would be hard to
know where the path came from otherwise.
.Pp
At the end of a succesful build, these lockfiles are removed.
The lock will stay around in case of errors.
.Po
raw
value from
.Xr wait 2
.Pc ,
and the name of the next task in the build pipeline (with todo=<nothing>
in case of failure during clean-up).
Normal list of tasks is:
.Ar depends prepare fetch patch configure build fake package clean .
.Pp
At the end of each job,
.Nm
rechecks the locks directory for existing lockfiles.
If some locks have vanished,
it will put the corresponding paths back in the queue and attempt
another build.
.Pp
This eases manual repairs: if a package does not build, the user can look
at the log, go to the port directory, fix the problem, and then remove the lock.
.Nm
will pick up the ball and keep building without interruption.
.Pp
It is perfectly safe to run several
.Nm
in parallel on the same machine.
This is not optimal, since each
.Nm
ignores the others, and only uses the lock info to avoid the other's
current work, but it can be handy: in an emergency, one can start a second
.Nm
to obtain a specific package right now, in parallel with the original
.Nm .
.Pp
Note that
.Nm
is very careful not to run two builds from the same pkgpath at the
same time, even on different machines:
in some cases, MULTI_PACKAGES and FLAVOR combinations may lead to the
same package being built simultaneously, and since the package repository
is shared, this can easily lead to trouble.
.Pp
Handling of shared log files and history is also done very carefully by
systematically appending to files or using atomic mv operations.
.Pp
For obvious reasons, this won't work as well with masters running on distinct
machines sharing their logs through NFS.
.Sh SHUTTING DOWN GRACEFULLY
.Nm
periodically checks for a file named
.Pa stop
in its log directory.
If this file exists, then it won't start new jobs, and shutdown when
the current jobs are finished unless
.Fl q .
.Pp
.Nm
also checks for files named
.Pa <hostname>-stop
in its log directory.
If such a file exists, then it won't start new jobs on
the corresponding machine.
.Sh FILES
Apart from producing packages,
.Nm
may create temporary files as
.Pa ${FULLDISTDIR}/${DISTFILE}.part .
.Pp
In fetch mode
.Po
.Fl f
and
.Fl F
.Pc ,
.Nm
populates
.Pa ${FULLDISTDIR}/by_cipher/sha256
with links.
It also uses
.Pa ${FULLDISTDIR}/distinfo
and
.Pa ${FULLDISTDIR}/history
as a
.Sq permanent log :
.Bl -tag -width distinfo
.It distinfo
cache of distfiles checksum.
Contains all
.Xr sha256 1
checksums of known files under
.Pa ${FULLDISTDIR} .
Fetching uses this to avoid re-checksumming known files.
.It history
Log of old files under distinfo.
After succesfully scanning a full ports tree
.Po
.Nm Fl a
.Pc ,
the fetch engine knows precisely which files are needed by the build
(and their checksums).
Anything that is
.Bl -bullet
.It
recorded in distinfo but unneeded
.It
recorded in distinfo but with the wrong checksum
.It
not recorded in distinfo, but not needed
.El
will be entered at the end of history as a line:
.Pp
.Li ts SHA256 (file) = value
.Pp
with
.Ar ts
a timestamp from Unix epoch.
.Pp
When cleaning up old files, with a tool such as
.Xr clean-old-distfiles 1 ,
it is vital to check both the checksum and
the file name: since mirroring stores permanent links under
.Pa by_cipher ,
files which are still needed will appear in history under their old
checksums, as an indication the link should be removed, but possibly not
the file itself.
.El
.Pp
If
.Pa ${DISTDIR}
ever becomes corrupted,
removing
.Pa ${DISTDIR}/distinfo
will force
.Nm
into checking all files again.
.Pp
.Nm
also records rolling build statistics under
.Pa ${DISTDIR}/build-stats/${ARCH} ,
and uses them automatically in the absence of
.Fl b Ar logfile .
.Pp
.Nm
will also create a large number of log files under
.Pa ${PORTSDIR}/logs/{$ARCH} :
.Bl -tag -width engine.log
.It Pa build.log
Actual build log.
Each line summarizes build of a single pkgpath, as:
.Sq pkgpath host time logsize (detailed timing)[!]
where time is the actual build time in seconds, host is the machine name
where this occurred, logsize is the corresponding log file size,
and a ! is appended in case the build didn't succeed.
.Pp
The detailed timing info gives a run-down of the build, with clean, fetch,
prepare, patch (actually extract+patch), configure, build, fake, package, clean
detailed timing info.
Note that the actual build time starts at
.Sq extract
and finishes at
.Sq package .
.It Pa clean.log
Paths that do not clean correctly, and required sudo to clean the directory.
.It Pa concurrent.log
Shows the actual concurrency achieved as a result of job starvation /
parallel handling.
Only gets a new line when the value changes: pid timestamp jobs
.It Pa dependencies.log
List of pkgpath frequencies, filled at end of LISTING if
.Fl a .
Will be automatically reused when restarting a build: a quick LISTING of
the most important dependencies will happen before the general LISTING.
.It Pa dist/<distfile>.log
Log of the
.Xr ftp 1
process(es) that attempted to fetch the distfile.
.It Pa engine.log
Build engine log.
Each line corresponds to a state change for a pkgpath and starts with the pid
of
.Nm ,
plus a timestamp of the log entry.
.Bl -tag -width BB:
.It ^
pkgpath temporarily put aside, because a job is running in the same directory.
.It !
pkgpath ignored, either directly, or indirectly because a dependency was
ignored.
End of the line states reason why ignored.
.It B
pkgpath built / distfile found.
.It E
error in build or fetch.
.It F
distfile queued for download.
.It I
pkgpath can be installed.
.It J
job to build pkgpath started.
Also records the host used for the build.
.It L
job did not start, existing lock detected.
.It N
job did not finish.
The host may have gone down.
.It P
built package is no longer required for anything.
.It Q
pkgpath queued as buildable whenever a slot is free.
.It T
pkgpath to build / distfile to download.
.It V
pkgpath put back in the buildable queue, after job that was running in
the same directory returned.
.El
.It Pa equiv.log
Lists of equivalent pkgpaths for the build, when default flavors and default subpackages have been resolved.
.It Pa fetch/bad.log
List of URLs that did not lead to a correct distfile, either because
they were not responding, or because of incorrect checksums.
.It Pa fetch/distfiles.log
Full list of distfiles seen through this build.
Can be used to remove old distfiles.
.It Pa fetch/good.log
List of URLs that fetched correctly, along with timing statistics.
.It Pa fetch/manually.log
List of pkgpaths that require manual intervention, in human-readable form.
.It Pa <hostname>-stop
Not a logfile at all, but created by the user to stop hostname creating
new jobs.
.It Pa <hostname>.sig.log
Complete library signature of the host.
.It Pa locks/
Directory where locks are created.
The slash in a pkgpath is replaced with a dot like so:
.Pa locks/devel.make
to flatten the structure.
.It Pa needed.log
list of needed dependencies at each point in time for each host when the
.Fl J
option has been used.
.It Pa packages/pkgname.log
one file or symlink per pkgname.
.It Pa paths/some/path.log
one file or symlink per pkgpath.
.It Pa rebuild.log
When using
.Fl R ,
contains the list of decisions to build/not rebuild a given pkgpath.
.It Pa signature.log
Discrepancies between hosts that prevent them from starting up.
.It Pa size.log
Size of work directory at the end of each build, built only with
.Fl s .
.It Pa stats.log
Simple log of the B=... line summaries.
Mostly useful for making plots and tweaking performance.
.It Pa stop
Not a logfile at all, but a file created by the user to stop
.Nm
creating new jobs.
.It Pa vars.log
Logs the directories that were walked in the ports tree for dependency
information, including the path to a dependency that triggered this
particular step.
.El
.Sh BUGS AND LIMITATIONS
.Nm
performs best with lots of paths to build.
When just used to build a few ports, there's a high risk of starvation
as there are bottlenecks in parts of the tree.
.Pp
Fetch jobs don't deal with checksum changes yet:
if a fetch fails because of a wrong checksum, if you update the distinfo
file and remove the lock,
.Nm
won't pick it up.
.Pp
Note that
.Nm
does not manage installed packages in any intelligent way, it will just
call
.Xr pkg_add 1
during its depend stage to install its dependencies.
With
.Fl u ,
it will call pkg_add -r.
With
.Fl U ,
it will call pkg_add -r -D installed,
but there is nothing else going on.
This is especially true when using
.Fl R ,
ensure the machine is clean of possibly older packages first, or run
.Nm
with
.Fl U .
.Pp
In particular
.Fl R
and
.Fl J
together may lead to strange issues.
.Pp
On heterogeneous networks, calibration of build info and choice of speed
factors is not perfect, and somewhat a dark art.
Using distinct speed factors on a build log that comes from a single
machine works fine, but using the build info coming from several machines
does not work all that well.
.Pp
.Nm
should check
.Pa /usr/include
and
.Pa /usr/X11R6/include
for consistency, but it doesn't.
.Pp
When an host fails consistency check, there is not yet a way to re-add it
after fixing the problem.
You have to stop
.Nm ,
cleanup and restart.
.Pp
There's a bug in
.Xr mfs 8
that prevents it from proper use in bulk builds.
.Pp
The default limits in
.Pa login.conf
are too small for bulk builds on any kind of parallel machines.
Bump number of processes.
.Pp
Even though
.Nm
tries really hard to check heterogeneous networks for sanity (checking
shared libraries and .la files), it is still dependent on the user to
make sure all the hosts build ports the same way.
.Pp
Make sure your NFS setup is consistent.
The ports dir itself should be exported, including distfiles and packages
repository, but the WRKOBJDIR should not be on NFS unless you have
absolutely no choice, or if you exhibit deep masochistic tendencies.
Pay particular attention to discrepancies in
.Pa /etc/mk.conf .
.Pp
Also,
.Nm
connects to external hosts through
.Xr ssh 1 ,
relying on
.Xr ssh_config 5
for any special cases.
.Sh SEE ALSO
.Xr clean-old-distfiles 1 ,
.Xr pkgpath 7
.Sh AUTHOR
Marc Espie
.Sh HISTORY
The original
.Nm dpb
command was written by Nikolay Sturm.
This version is a complete rewrite from scratch using all the stuff
we learnt over the years to make it better.
.Pp
There are still a number of changes to make, and some possible avenues
to explore.
.Pp
Better build feedback for next builds would be nice: we need a way to
calibrate build logs that contain info for several machines (so that we
can gauge whether a machine is fast or slow).
It might make sense to have some kind of machine affinity for big packages
in a cluster, so that we avoid reinstalling big things on each machine if
we can get away with installing stuff on a single machine.
We should probably keep the pkgnames around with the pkgpath in the build-log,
so that we give more credibility to build times that correspond to the
exact same pkgnames.