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Diffstat (limited to 'README')
| -rw-r--r-- | README | 34 |
1 files changed, 22 insertions, 12 deletions
@@ -4,20 +4,23 @@ mwrap is designed to answer the question: Which lines of Ruby are hitting malloc the most? -mwrap wraps all malloc, calloc, and realloc calls to trace the Ruby -source location of such calls and bytes allocated at each callsite. -This functionality may be expanded in the future. - -It does not track allocation lifetimes, or frees, however. It works -best for allocations under GVL, but tries to track numeric caller -addresses for allocations made without GVL so you can get an idea of how -much memory usage certain extensions and native libraries use. +mwrap wraps all malloc-family calls to trace the Ruby source +location of such calls and bytes allocated at each callsite. +As of mwrap 2.0.0, it can also function as a leak detector +and show live allocations at every call site. Depending on +your application and workload, the overhead is roughly a 50% +increase memory and runtime. + +It works best for allocations under GVL, but tries to track +numeric caller addresses for allocations made without GVL so you +can get an idea of how much memory usage certain extensions and +native libraries use. It requires the concurrent lock-free hash table from the Userspace RCU project: https://liburcu.org/ -It does not require recompiling or rebuilding Ruby, but only supports -Ruby trunk (2.6.0dev+) on a few platforms: +It does not require recompiling or rebuilding Ruby, but only +supports Ruby trunk (2.6.0dev+) on a few platforms: * GNU/Linux * FreeBSD (tested 11.1) @@ -45,10 +48,12 @@ variable to append the results to a log file: sort -k1,1rn </path/to/log | $PAGER You may also `require "mwrap"' in your Ruby code and use -Mwrap.dump, Mwrap.clear, Mwrap.reset, Mwrap.each, etc. +Mwrap.dump, Mwrap.reset, Mwrap.each, etc. However, mwrap MUST be loaded via LD_PRELOAD to have any -effect in tracking malloc use. +effect in tracking malloc use. However, it is safe to keep +"require 'mwrap'" in performance-critical deployments, +as overhead is only incurred when used as an LD_PRELOAD. The output of the mwrap dump is a text file with 3 columns: @@ -59,6 +64,11 @@ or an address retrieved by backtrace_symbols(3). It is recommended to use the sort(1) command on either of the first two columns to find the hottest malloc locations. +mwrap 2.0.0+ also supports a Rack application endpoint, +it is documented at: + + https://80x24.org/mwrap/MwrapRack.html + == Known problems * 32-bit machines are prone to overflow (WONTFIX) |