Why projects? Why not?

One of the questions I often ask myself is “why aren’t more sites using projects?”. As I wander from forum to forum, I regularly see people saying, “I want to consolidate three [application server] instances on my system”—or two [database] instances or n applications. Many of these applications need to run with identical credentials (user id, group id, authorizations, privileges, etc.) and are only distinguishable by their working directory, environment variables, or the like. Reading these requests is a bit frustrating, as this scenario is one of the key motivations we had when introducing the project(4) database—and I can only conclude that it’s my failure to really communicate its utility.

Projects let you assign a label with a specific workload. In S8 6/00 and all subsequent releases, you can explicitly launch a workload with its appropriate project using the newtask(1) command. If extended accounting has been activated using acctadm(1M) with one of the standard record groupings, then the processes within that workload will include their project ID. Writing an accounting record on every process exit can impact some workloads, so you can optionally choose to only write records when every task exits. A task is a new process collective that groups related work within a workload (so it could be a workload component, like a batch submission). acctadm(1M) will report on the current status of the extended accounting subsystem, if invoked without arguments:

$ acctadm
Task accounting: inactive
Task accounting file: none
Tracked task resources: none
Untracked task resources: extended
Process accounting: inactive
Process accounting file: none
Tracked process resources: none
Untracked process resources: extended,host,mstate
Flow accounting: inactive
Flow accounting file: none
Tracked flow resources: none
Untracked flow resources: extended
The resource line is reporting what accounting resource groups and resources we can include in each record. We can expand the resource groups for each type of accounting using the

-r option.

$ acctadm -r
extended pid,uid,gid,cpu,time,command,tty,projid,taskid,ancpid,wait-status,zone,flag
basic    pid,uid,gid,cpu,time,command,tty,flag
extended taskid,projid,cpu,time,host,mstate,anctaskid,zone
basic    taskid,projid,cpu,time
extended saddr,daddr,sport,dport,proto,dsfield,nbytes,npkts,action,ctime,lseen,projid,uid
basic    saddr,daddr,sport,dport,proto,nbytes,npkts,action
So we can enable the extended task record by invoking

acctadm(1M) like

# acctadm -e extended task

acctadm -E task

acctadm -f /var/adm/exacct/task

In S10, you can optionally enable accounting without having it write to a file, such that the records are retrievable using getacct(2).

Of course, that’s all about accounting, but projects are useful even if you’re not interested in the long term resource consumption of your workloads. The project ID is useful for isolating your workload using conventional /proc-based tools like prstat(1M) and pgrep(1), as well as with DTrace. For instance to see only one’s own projects, you can use the -J option to pgrep.

$ pgrep -lf -J user.sch
728069 /usr/bin/bash
728027 /usr/bin/bash
125169 /usr/bin/bash

To see workloads on the system, you can use

prstat‘s -J option, which aggregates the activity by project ID, as well as displaying the most active processes:

$ prstat -c -J user.sch 1 1
653322 xx         19M   17M cpu2     0    3 166:34:10  12% setiathome/1
911046 xx         19M   17M cpu5     0    3 170:28:53  12% setiathome/1
668697 xx         19M   17M cpu4     0    3 138:53:14  12% setiathome/1
100378 daemon   2352K 1944K sleep   60  -20  30:18:23 0.2% nfsd/5
125214 sch      4472K 4152K cpu3     1    0   0:00:00 0.0% prstat/1
100066 root     7872K 6736K sleep   29    0   2:20:42 0.0% picld/13
125169 sch      2768K 2416K sleep    1    0   0:00:00 0.0% bash/1
100156 root       91M   36M sleep   59    0   0:46:59 0.0% poold/8
100249 root     6680K 4848K sleep    1    0   8:02:46 0.0% automountd/2
100254 root     5776K 3552K sleep   59    0   0:00:01 0.0% fmd/10
100262 root     4024K 3424K sleep   59    0   0:19:40 0.0% nscd/57
100265 root     1248K  776K sleep   59    0   0:00:00 0.0% sf880drd/1
100184 root     2288K 1384K sleep    1    0   0:00:00 0.0% ypbind/1
100172 daemon   2680K 1704K sleep   58    0   1:07:32 0.0% rpcbind/1
100158 root     2216K 1336K sleep   59    0   0:00:26 0.0% in.routed/1
130        3   56M   51M   0.3% 475:56:17  37% background
0       61  341M  168M   1.0%  43:21:28 0.3% system
36565        4   13M   11M   0.1%   0:00:01 0.1% user.sch
105403       14   39M   30M   0.2%   0:00:03 0.0% user.xxxxxxx
77194       17   74M   62M   0.4%   0:03:10 0.0% user.xxxxxx
Total: 133 processes, 279 lwps, load averages: 3.07, 3.07, 3.04

(This system’s pretty idle during our U.S. shutdown, so it’s doing its best to find extraterrestrial customers.)

To limit your DTrace predicates to only a project of interest, use the curpsinfo built-in variable to access the pr_projid field, like

/curpsinfo->pr_projid == $projid && ..../

where I’ve also used the

$projid scripting macro, which expands to the result of curprojid(2) for the running DTrace script. You could instead explicitly enter your project ID of interest, or use one of the argument macros if writing a script you expect to reuse.

Projects also let you place resource controls on your workload, establish its resource pool bindings, and more. We’ll make it easier to use them with the forthcoming service management facility. But I’ll summarize: projects are a precise and efficient way to label your workloads (as opposed to pattern matching on arguments or environment variables). If you are consolidating workloads, either because of machine eliminations, organizational mergers, or other reasons, they are definitely worth considering. If you think there’s a way to make them more applicable to your work, please let me know.