Update default_chunk_cache_size

[WardF]

• Fixes Severe performance degradation in 4.9.3-rc2 #3067

[edwardhartnett]

Really? This solves it?

[WardF]

Really? This solves it?

This solves it. I'm playing around with a smaller (small enough to be part of version control) test file to see if I can incorporate this into our CI. In the meantime, here's the test directory/script I was using, modified from the script I tossed together for the initial git-bisect.

• test.zip

[WardF]

The results observed on my system:

vagrant@ubuntu2410gdm:~/Desktop/test/netcdf-c$ ../mytest.sh 
	o Default chunk cache size: 67108864 (should pass)
		o Configuring
		o Building
		o Installing to temporary location /home/vagrant/tmp
		o Running test program. Expected to pass.
Storm 13408: Latitude is 13.800000, Time taken = 30.770 ms
Storm 13409: Latitude is 12.400000, Time taken = 0.021 ms
Storm 13410: Latitude is 16.799999, Time taken = 0.006 ms
Storm 13411: Latitude is -10.300000, Time taken = 0.005 ms
Storm 13412: Latitude is -12.700000, Time taken = 0.003 ms
Storm 13413: Latitude is 12.400000, Time taken = 0.004 ms
Storm 13414: Latitude is -11.000000, Time taken = 0.004 ms
Storm 13415: Latitude is 10.400000, Time taken = 0.005 ms
Storm 13416: Latitude is -11.900000, Time taken = 0.004 ms
Storm 13417: Latitude is -17.299999, Time taken = 0.004 ms

Average runtime per iteration: 3.083 ms

-------------------------------------

	o Default chunk cache size: 16777216U (should fail)
		o Configuring
		o Building
		o Installing to temporary location /home/vagrant/tmp
		o Running test program. Expected to fail.
Storm 13408: Latitude is 13.800000, Time taken = 31.398 ms
Storm 13409: Latitude is 12.400000, Time taken = 29.782 ms
Storm 13410: Latitude is 16.799999, Time taken = 29.809 ms
Storm 13411: Latitude is -10.300000, Time taken = 29.954 ms
Storm 13412: Latitude is -12.700000, Time taken = 29.813 ms
Storm 13413: Latitude is 12.400000, Time taken = 29.798 ms
Storm 13414: Latitude is -11.000000, Time taken = 29.898 ms
Storm 13415: Latitude is 10.400000, Time taken = 29.955 ms
Storm 13416: Latitude is -11.900000, Time taken = 30.043 ms
Storm 13417: Latitude is -17.299999, Time taken = 29.906 ms

Average runtime per iteration: 30.036 ms
	o [x] Error caught.
vagrant@ubuntu2410gdm:~/Desktop/test/netcdf-c$