A tool to evaluate methods in creating temp files
This "CreateTempFilesPerfEval" tool is to compare the time cost of
creating temporary files between using GetTempFileName Windows API and
using the GUID-based method, especially when there are already tens of
thousands of temp files in the target directory.
Sample results from a corp desktop (Windows 10 Enterprise, version
1511) are recorded in GetTempFileNamePerfExample.txt and
GuidPerfExample.txt in this CL. It shows the time cost of creating
every 500 temp files until there are 65535 temp files created in a
directory for each method. The last row shows the time cost of
creating the very last 35 temp files. Note that GetTempFileName can
create at most 65535 files in a single directory.
The sample results (the last row ommited) are also plotted in
https://docs.google.com/spreadsheets/d/1j5nHneABic4-Ziz7KjjXPAbvr2aERyZB0qwbLYqyKGE/edit#gid=0
From the data/figure, we can see that GetTempFileName is working fine
when the amount of temp files in the folder is under ~36000. It takes
~400 ms to create 500 temp files. However,
1) As the temp files accumulate to 36500, it performs ~4x worse;
2) As the temp files accumulate to 52000, it performs ~9x worse;
3) As the temp files accumulate to 60000, it performs ~15x worse;
4) As the temp files accumulate to 64500, it performs ~50x worse;
5) As the temp files accumulate to 65000, it performs ~110x worse;
-- Now it takes 43+ seconds to create 500 temp files.
6) As the temp files accumulate to 65500, it performs ~1570x worse;
-- It takes 44+ seconds just to create the remaining 35 temp files.
In comparison, creating temp files using GUID-based method doesn't
have this performance issue. It always takes 400 ms ~ 500 ms to create
500 temp files. The time complexity of GUID-based method for creating
temp files is O(1) w.r.t the amount of existing temp files in the
target directory.
BUG=711534,103737
Review-Url: https://codereview.chromium.org/2810333008
Cr-Original-Commit-Position: refs/heads/master@{#465438}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 4cb75df89a5fabfb4a83717cdc0f9289eb3b0596
7 files changed
