Is there any alterntive to wait3 to get rusage structure in shell scripting?

Question

I was trying to monitor the peak memory usage of a child process.time -v is an option,but it is not working in solaris.So is there any way to get details that are in rusage structure from shell scripting?

Answer 1

You can use /usr/bin/timex

From the /usr/bin/timex man page:

The given command is executed; the elapsed time, user time and system time spent in execution are reported in seconds. Optionally, process accounting data for the command and all its children can be listed or summarized, and total system activity during the execution interval can be reported.

...

-p List process accounting records for command and all its children. This option works only if the process accounting software is installed. Suboptions f, h, k, m, r, and t modify the data items reported. The options are as follows:

...

Start with the man page for acctadm to get process accounting enabled.

Note that on Solaris, getrusage() and wait3() do not return memory usage statistics. See the (somewhat dated) getrusage() source code at http://src.illumos.org/source/xref/illumos-gate/usr/src/uts/common/syscall/rusagesys.c and the wait3() source code at http://src.illumos.org/source/xref/illumos-gate/usr/src/lib/libbc/libc/sys/common/wait.c#158 (That's actually OpenSolaris source, which Oracle dropped support for, and it may not represent the current Solaris implementation, although a few tests on Solaris 11.2 show that the RSS data is in fact still zero.)

Also, from the Solaris getrusage() man page:

The ru_maxrss, ru_ixrss, ru_idrss, and ru_isrss members of the rusage structure are set to 0 in this implementation.

There are almost certainly other ways to get the data, such as dtrace.

Edit:

dtrace doesn't look to be much help, unfortunately. Attempting to run this dtrace script with dtrace -s memuse.d -c bash

#!/usr/sbin/dtrace -s

#pragma D option quiet

profile:::profile-1001hz
/ pid == $target /
{
    @pct[ pid ] = max( curpsinfo->pr_pctmem );
}

dtrace:::END
{
    printa( "pct: %@u %a\n", @pct );
}

resulted in the following error message:

dtrace: failed to compile script memuse.d: line 8: translator does not define conversion for member: pr_pctmem

dtrace on Solaris doesn't appear to provide access to process memory usage. In fact, the Solaris 11.2 /usr/lib/dtrace/procfs.d translator for procfs data has this comment in it:

/*
 * Translate from the kernel's proc_t structure to a proc(4) psinfo_t struct.
 * We do not provide support for pr_size, pr_rssize, pr_pctcpu, and pr_pctmem.
 * We also do not fill in pr_lwp (the lwpsinfo_t for the representative LWP)
 * because we do not have the ability to select and stop any representative.
 * Also, for the moment, pr_wstat, pr_time, and pr_ctime are not supported,
 * but these could be supported by DTrace in the future using subroutines.
 * Note that any member added to this translator should also be added to the
 * kthread_t-to-psinfo_t translator, below.
 */

Browsing the Illumos.org source code, searching for ps_rssize, indicates that the procfs data is computed only when needed, and not updated continually as the process runs. (See http://src.illumos.org/source/search?q=pr_rssize&defs=&refs=&path=&hist=&project=illumos-gate)