1. What Python can learn
from Java
jbellis@datastax.com
Saturday, September 10, 2011

2. Saturday, September 10, 2011

3. (Not a web development perspective)
Saturday, September 10, 2011

4. Lesson one: GC
✤ Hotspot GC
✤ Pluggable
✤ Well-documented (http://java.sun.com/j2se/reference/
whitepapers/memorymanagement_whitepaper.pdf)
✤ Tuneable (http://www.slideshare.net/ludomp/gc-tuning-in-the-
hotspot-java-vm-a-fisl-10-presentation)
Saturday, September 10, 2011

5. Troubleshooting OOM
Saturday, September 10, 2011

6. Troubleshooting fragmentation
http://www.cloudera.com/blog/2011/02/avoiding-full-gcs-in-hbase-with-memstore-local-allocation-buffers-part-2/
Saturday, September 10, 2011

7. Lesson 2: Concurrency
✤ For CPU-bound applications, copies are the enemy
✤ Corollary: you need to support threads + shared state
✤ Actor model
✤ Multi-process + sysv
Saturday, September 10, 2011

8. java.util.concurrent: ahead of its time
✤ ConcurrentSkipListMap
✤ CopyOnWriteArrayList
✤ NonblockingHashMap*
✤ Atomic[Int|Long|Reference|...]
✤ SynchronousQueue
✤ Java 7: TransferQueue
✤ ThreadPoolExecutor, ScheduledThreadPoolExecutor
✤ FutureTask
Saturday, September 10, 2011

9. Shared state = good, Mutable state = bad
✤ guava: Immutable collections
✤ http://code.google.com/p/guava-libraries/
✤ Persistent collections
✤ http://code.google.com/p/pcollections/
✤ (More accurately, “What Python can learn from Haskell”)
Saturday, September 10, 2011