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Re: [pdt-dev] H2Cache questions


I made some Java and SQL optimization:
* Indexes
* Replace subquery by inner joins
* Remove 1=1 from where ;)
* Tweaks on H2ConnectionFactory

Now on large project in my test environment, h2cache is not required. For me, everything is faster, less memory usage.

Here is my experiment: https://github.com/zulus/dltk.core/commit/5be4dc62ffed6c19a431b91915c1b9010c7363bb

How Iâm testing:
  1. 2 large Symfony 2 projects in workspace
  2. Enable all highlighters
  3. Open 2k file with many nested call
  4. Format your file , next run CA
  5. Check your profiler ;)
  1. faster eclipse startup !
  2.  Open PHP type always working (without âwait for indexerâ)
Before I send a patch to bugzilla, I have to perform some code cleanup. I also see two other points for optimization in h2 indexer.

Dawid PakuÅa 
+48 795 996 064

From: Kaloyan Raev kaloyan.r@xxxxxxxx
Reply: PDT Developers pdt-dev@xxxxxxxxxxx
Date: 23 paÅdziernika 2013 at 09:30:15
To: PDT Developers pdt-dev@xxxxxxxxxxx
Subject:  Re: [pdt-dev] H2Cache questions

The test I ran yesterday for only for importing huge existing project in the workspace. There is a search operation for each file before it is indexed (to avoid indexing the same file twice). In this case the h2 cache is indeed an overhead because most of the time the searched file isn't available neither in the h2 cache, nor in the h2 db. 

Today, I ran an additional test - I searched for a method reference in this same huge project. Well, without the cache this operation is 3 times slower. My system is with SSD. I guess that on HDD it will be even more slower.

So, it's seems that the h2 cache really optimizes search operations.


On Tue, Oct 22, 2013 at 6:35 PM, Alexey Panchenko <alex.panchenko@xxxxxxxxx> wrote:
Hi Kaloyan,

How often does your performance test execute search operations? what operations are executed at all in the test?

I afraid this indexer at the moment is used only by PDT, so I don't have any performance data.


On Tue, Oct 22, 2013 at 8:59 PM, Kaloyan Raev <kaloyan.r@xxxxxxxx> wrote:
Hi again, 

I did a quick experiment with removing H2Cache. My performance tests show slight improvement without this cache. 

Alex, I'll be curious to hear if it's the same in your adopter's product. Here is a commit to cherry pick: https://github.com/kaloyan-raev/dltk.core/commit/e8bfa12aa5408341d230c57530474db281ef132c


On Mon, Oct 21, 2013 at 10:10 AM, Kaloyan Raev <kaloyan.r@xxxxxxxx> wrote:
Hi Alex, 

The same thoughts crossed my mind when I worked on improving the performance in Zend Studio a couple of months ago. 

H2Cache is a set of maps with strong references, which makes it really look more like an in-memory copy of the h2 db, rather than a cache. Over time, I suspect, this may cause memory consumption problems. 

I suppose that the H2Cache was introduced in the past, because of some inefficiencies in the h2 db schema - remember eclip.se/415137. But now, when the necessary index is added to the schema, the benefits of H2Cache are not really visible.

One of the idea in my todo list for performance optimizations is indeed to try removing the H2Cache and measure the impact. Unfortunately, I was distracted from the performance topic with other things, but I hope I'll be back on it very soon.


On Sat, Oct 19, 2013 at 10:13 AM, Alexey Panchenko <alex.panchenko@xxxxxxxxx> wrote:
Hi PDT-team,

I have some questions regarding this class

which was contributed some time ago by Michael and committed by Roy.

As I understand the code, it looks like *all* the data from SQL database is loaded into this class and then updates happen to both the in-memory copy and the underlying SQL database.
For me, that effectively compromises the SQL database, as the same result could be reached with eventually saving data to file using java serialization.

So, I am curious of the following:
- how much memory does it use?
- is it supposed to be a cache (and contain recently used data) or a full in-memory copy?
- how much does it improve the performance? Can the same effect be reached in other ways?


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