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.TH uobjnew 8 "2016-11-07" "USER COMMANDS"
.SH NAME
uobjnew, javaobjnew, rubyobjnew, cobjnew \- Summarize object allocations in
high-level languages.
.SH SYNOPSIS
.B javaobjnew [-h] [-C TOP_COUNT] [-S TOP_SIZE] [-v] pid [interval]
.br
.B rubyobjnew [-h] [-C TOP_COUNT] [-S TOP_SIZE] [-v] pid [interval]
.br
.B cobjnew [-h] [-C TOP_COUNT] [-S TOP_SIZE] [-v] pid [interval]
.br
.B uobjnew [-h] [-C TOP_COUNT] [-S TOP_SIZE] [-v] [-l {java,ruby,c}] pid [interval]
.SH DESCRIPTION
uobjnew traces object allocations in high-level languages (including "malloc")
and prints summaries of the most frequently allocated types by number of
objects or number of bytes.
This tool relies on USDT probes embedded in many high-level languages, such as
Node, Java, Python, and Ruby. It requires a runtime instrumented with these
probes, which in some cases requires building from source with a USDT-specific
flag, such as "--enable-dtrace" or "--with-dtrace". For Java, the Java process
must be started with the "-XX:+ExtendedDTraceProbes" flag.
Since this uses BPF, only the root user can use this tool.
.SH REQUIREMENTS
CONFIG_BPF and bcc.
.SH OPTIONS
.TP
\-C TOP_COUNT
Print the top object types sorted by number of instances.
.TP
\-S TOP_SIZE
Print the top object types sorted by size.
.TP
\-v
Print the resulting BPF program, for debugging purposes.
.TP
{java,ruby,c}
The language to trace.
.TP
pid
The process id to trace.
.TP
interval
Wait this many seconds and then print the summary and exit. By default, wait
for Ctrl+C to exit.
.SH EXAMPLES
.TP
Trace object allocations in a Ruby process:
#
.B uobjnew ruby 148
.TP
Trace object allocations from "malloc" and print the top 10 by total size:
#
.B uobjnew -S 10 c 1788
.SH FIELDS
.TP
TYPE
The object type being allocated. For C (malloc), this is the block size.
.TP
ALLOCS
The number of objects allocated.
.TP
BYTES
The number of bytes allocated.
.SH OVERHEAD
Object allocation events are quite frequent, and therefore the overhead from
running this tool can be considerable. Use with caution and make sure to
test before using in a production environment. Nonetheless, even thousands of
allocations per second will likely produce a reasonable overhead when
investigating a problem.
.SH SOURCE
This is from bcc.
.IP
https://github.com/iovisor/bcc
.PP
Also look in the bcc distribution for a companion _example.txt file containing
example usage, output, and commentary for this tool.
.SH OS
Linux
.SH STABILITY
Unstable - in development.
.SH AUTHOR
Sasha Goldshtein
.SH SEE ALSO
ustat(8), ugc(8), memleak(8)