Slow readng tzdb.dat

[Xueming Shen]

Hi Salter,

Thanks for the report and suggested fix, I have filed a bug for this issue.
Yes, it probably will trigger a slow loading if run on a "high-latency" remote
file system. There was a BufferredInputstram wrapper at the beginning,
then I guess it got dropped during performance measure/testing, on local
local file system. Will get it fixed.

https://bugs.openjdk.java.net/browse/JDK-8026197

thanks!
-Sherman

On 10/09/2013 10:08 AM, Salter, Thomas A wrote:
> I noticed recently that the JDK8 JVM was very slow starting on systems where the JRE is on a high-latency, remote file system.  I tracked this down to the reading of tzdb.dat.  In java/time/zone/TzdbZoneRulesProvider.java and sun/util/calendar/ZoneInfoFile.java the tzdb.dat file is read using a DataInputStream directly over a FileInputStream.  Consequently there ends up being a large number of very small (often a single byte) read requests to the underlying O/S file system.  This can be fixed trivially by adding a BufferedInputStream between the DataInputStream and the FileInputStream.
>
> Thus this:
>    try (DataInputStream dis = new DataInputStream(
>             new FileInputStream(new File(libDir, "tzdb.dat")))) {
> becomes:
>    try (DataInputStream dis = new DataInputStream(
>        new BufferedInputStream(
>             new FileInputStream(new File(libDir, "tzdb.dat")), 32000))) {
>