Brew afsctool on your own for Mac OS Sierra

Recently, I came across an error message while compressing the document with HFS+ compression using open source tool afsctool. The repository on Homebrew project is still on version 1.6.4.

Message comes up every time: "Unable to compress file."

Someone on Github has figured out what's happening and has a solution. The Github user has pointed out that the filesystem on Sierra returns a different value of file type than its predecessor. This renders afsctool useless and return error message at all time. But the suggested change has never been updated on the original source repository of afsctool.

With a little patience for not using this tool, I made up my mind. I think it's time to homebrew our software tool before the Author patches the source code for this.

Here's the recipe:

Before your own compiling work, you might want to uninstall the outdated brew formula for afsctool:

$
$ brew uninstall afsctool

Make sure gcc is installed properly on your Mac.

Take a look at the Hombrew formulas for afsctool via http://brewformulas.org/Afsctool

Take a look at the source file from there: https://github.com/Homebrew/homebrew-core/tree/master/Formula/afsctool.rb

We found a URL from there: https://docs.google.com/uc?export=download&id=0BwQlnXqL939ZQjBQNEhRQUo0aUk

Also, take a look at the parameters called from the def() function call. Highlighted parameters will be useful for compiling:

def install
    cd "afsctool_34" do
      system ENV.cc, ENV.cflags, "-lz",
         "-framework", "CoreServices", "-o", "afsctool", "afsctool.c"
      bin.install "afsctool"
    end
end

Grab the source code ZIP of afsctool from the above URL.

Extract the ZIP file to a temporary location.

Find afsctool.c and amend the file according to this Github post.

Try compiling the .c file afsctool.c with GCC compiler using the aforementioned parameters from brew formula:

$
$ gcc -lz -framework CoreServices -o afsctool afsctool.c

Copy the compile file afsctool to the common bin folder for easy access:

$
$ cp ./afsctool /usr/local/bin/afsctool

Well, it's time to have a try on our new compiled tool:

$ afsctool -cv ./afsctool.c
/afsctool_34/afsctool.c:
File content type: public.c-source
File size (uncompressed data fork; reported size by Mac OS 10.6+ Finder): 79339 bytes / 79 KB (kilobytes) / 77 KiB (kibibytes)
File size (compressed data fork - decmpfs xattr; reported size by Mac OS 10.0-10.5 Finder): 13396 bytes / 16 KB (kilobytes) / 16 KiB (kibibytes)
File size (compressed data fork): 13412 bytes / 16 KB (kilobytes) / 16 KiB (kibibytes)
Compression savings: 83.1%
Number of extended attributes: 4
Total size of extended attribute data: 50 bytes
Approximate overhead of extended attributes: 1608 bytes
Approximate total file size (compressed data fork + EA + EA overhead + file overhead): 18306 bytes / 18 KB (kilobytes) / 18 KiB (kibibytes)

Finally, the compression works again.

By the way, we may need to keep watching until one day an updated brew formula is available to tackle this problem for Sierra.

Windows 2012 ports exhausted under heavy load

For a test case scenario, I have encountered a port depletion on Windows 2012 server which has its available ports used up quickly due to frequent queries to the database and HTTP requests to web server. Thing happened within a short period of time and nothing can ease the situation except a system reboot. Too many ports are opened but not closed properly which could be mainly due to the arriving order of incoming packets being out of sync.

Here's the extract of resolution:

On Windows platforms, the default timeout is 120 seconds, and the maximum number of ports is approximately 4,000, resulting in a maximum rate of 33 connections per second. If your index has four partitions, each search requires four ports, which provides a maximum query rate of 8.3 queries per second.

(maximum ports/timeout period)/number of partitions = maximum query rate

If this rate is exceeded, you may see failures as the supply of TCP/IP ports is exhausted. Symptoms include drops in throughput and errors indicating failed network connections. You can diagnose this problem by observing the system while it is under load, using the netstat utility provided on most operating systems.

To avoid port exhaustion and support high connection rates, reduce the TIME_WAIT value and increase the port range.

This problem does not usually appear on UNIX systems due to the higher default connection rate in those operating systems.

To set TcpTimedWaitDelay (TIME_WAIT):

    Use the regedit command to access the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\ Services\TCPIP\Parameters registry subkey.

1.     Create a new REG_DWORD value named TcpTimedWaitDelay.
2.     Set the value to 60.
3.     Stop and restart the system.

To set MaxUserPort (ephemeral port range):

    Use the regedit command to access the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\ Services\TCPIP\Parameters registry subkey.

1.     Create a new REG_DWORD value named MaxUserPort.
2.     Set this value to 32768.
3.     Stop and restart the system.

Furthermore, you may have to set another parameter StrictTimeWaitSeqCheck as well, for TcpTimedWaitDelay to be of effect:

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]
"StrictTimeWaitSeqCheck"=dword:00000001

Setting or changing these will require a reboot for the changes to be in effect.