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authorroberto2010-12-09 18:40:34 (EST)
committerroberto2010-12-09 18:46:47 (EST)
commit941b3d8a8105333ccbc15e3b57574fce6da6f006 (patch)
tree1696100d15d2655e2e70c5efc8cdac646599cdb5
parentc181e1ab8ac52ff8ce02f95affc8f79cfbfff323 (diff)
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IndexPack: Remove blob-streaming size thresholdrefs/changes/00/2100/1
Always use streaming (for SHA-checksum & collision detection) when indexing whole blobs, regardless of their size. Positives: * benefits of bugfix #312868 will apply to all runtimes, without additional conf for mem-constrained JVMs (5MB huge for some) * no byte array allocation (re-uses readBuffer instead of allocating new full-size array) * mildly better overall performance (given the usual blob-does-not-need-collision-checking case) * removes unnecessary code Negative: * doubles the disk IO for a blob comparision (comparitively rare occurance) I perf-tested a range of threshold sizes against a random selection of packfiles I found on my harddrive, the results are here: https://spreadsheets.google.com/ccc?key=tLCQElyyd2RKN9QevfvgwGQ&hl=en_GB#gid=1 My interpretation of the results is that the streaming size threshold isn't beneficial (actually seems to be very slightly detrimental) -so we should just get rid of it. This tallies with some of the comments Shawn & I had for the default value of streamFileThreshold in the review for I862afd4c: http://egit.eclipse.org/r/#patch,sidebyside,2040,2,org.eclipse.jgit/src/org/eclipse/jgit/transport/IndexPack.java The perf-test code is here: https://gist.github.com/735402 It's a bit scruffy but basically does 10 runs (in randomised order) for each threshold size on various packfiles, waiting a second between each pack-indexing to allow GC to catch up. I know it's not perfect - proper perf testing is hard to do :-)
-rw-r--r--org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/IndexPackTest.java1
-rw-r--r--org.eclipse.jgit/src/org/eclipse/jgit/transport/IndexPack.java9
2 files changed, 1 insertions, 9 deletions
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/IndexPackTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/IndexPackTest.java
index 6015428..6592905 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/IndexPackTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/IndexPackTest.java
@@ -166,7 +166,6 @@ public class IndexPackTest extends RepositoryTestCase {
final byte[] raw = pack.toByteArray();
IndexPack ip = IndexPack.create(db, new ByteArrayInputStream(raw));
- ip.setStreamFileThreshold(1);
ip.index(NullProgressMonitor.INSTANCE);
ip.renameAndOpenPack();
}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/IndexPack.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/IndexPack.java
index 8feb483..bb9edc2 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/IndexPack.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/IndexPack.java
@@ -145,8 +145,6 @@ public class IndexPack {
private final Repository repo;
- private int streamFileThreshold;
-
/**
* Object database used for loading existing objects
*/
@@ -244,7 +242,6 @@ public class IndexPack {
public IndexPack(final Repository db, final InputStream src,
final File dstBase) throws IOException {
repo = db;
- streamFileThreshold = 5 * (1 << 20); // A reasonable default for now.
objectDatabase = db.getObjectDatabase().newCachedDatabase();
in = src;
inflater = new InflaterStream();
@@ -268,10 +265,6 @@ public class IndexPack {
}
}
- void setStreamFileThreshold(int sz) {
- streamFileThreshold = sz;
- }
-
/**
* Set the pack index file format version this instance will create.
*
@@ -860,7 +853,7 @@ public class IndexPack {
objectDigest.update((byte) 0);
boolean checkContentLater = false;
- if (type == Constants.OBJ_BLOB && sz >= streamFileThreshold) {
+ if (type == Constants.OBJ_BLOB) {
InputStream inf = inflate(Source.INPUT, sz);
long cnt = 0;
while (cnt < sz) {