commit 6b1b8a9dbd6e4796d5777d676050d45305ec163e
author janakr <janakr@google.com> Fri Nov 10 23:20:22 2017 +0100
committer Damien Martin-Guillerez <dmarting@google.com> Sun Nov 12 18:37:50 2017 +0100
tree 7e74fec447263315d5656022a296f3e29b20d1cc
parent 1c639ab3d40ca5ae38440d7c0ee01248707c5da3

RELNOTES: --keep_incrementality_data flag allows Bazel servers to be run in memory-saving non-incremental mode independent of --batch and --discard_analysis_cache.

A command run with --nokeep_incrementality_data will discard data that would be needed for incremental builds. Subsequent commands can be sent to the same server, but they will not get the benefit of incrementality from this command. However, if --keep_incrementality_data is specified on a subsequent command, the commands after that will get the benefits of incrementality.

There are two benefits to not being dependent on --batch. First, this allows Bazel servers to be run in extreme memory-saving mode without the startup penalties (JVM startup, JITting) that --batch execution imposes. Second, this allows Bazel developers to inspect the state of a Bazel server after an extreme memory-saving build.

In order to avoid discarding data unnecessarily (for instance, on a "bazel info used-heap-size-after-gc" or "bazel dump --skyframe=summary") the actual resetting of the graph is done lazily, right before its use in SequencedSkyframeExecutor#sync. This is morally a partial rollback of https://github.com/bazelbuild/bazel/commit/98cd82cbdcac7c48164a611c5a9aa8fc2f1720ef.

For now, our tests specify all of the flags. After this change sticks, I plan to get rid of the --batch flag from these tests, which should allow for some clean-ups. Eventually --batch and --discard_analysis_cache may not imply that we don't keep incremental state: we can require that it be specified explicitly.

PiperOrigin-RevId: 175335075

src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java

diff --git a/src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java b/src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java
index 24d859a..e878b6f 100644
--- a/src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java
+++ b/src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java
@@ -437,10 +437,9 @@
       executor.executionPhaseStarting();
       skyframeExecutor.drainChangedFiles();
 
-      if (request.getViewOptions().discardAnalysisCache) {
-        // Free memory by removing cache entries that aren't going to be needed. Note that in
-        // skyframe full, this destroys the action graph as well, so we can only do it after the
-        // action graph is no longer needed.
+      if (request.getViewOptions().discardAnalysisCache
+          || !request.getBuildOptions().keepIncrementalityData) {
+        // Free memory by removing cache entries that aren't going to be needed.
         env.getSkyframeBuildView()
             .clearAnalysisCache(analysisResult.getTargetsToBuild(), analysisResult.getAspects());
       }
@@ -685,7 +684,7 @@
       ActionCache actionCache,
       SkyframeExecutor skyframeExecutor,
       ModifiedFileSet modifiedOutputFiles) {
-    BuildRequest.BuildRequestOptions options = request.getBuildOptions();
+    BuildRequestOptions options = request.getBuildOptions();
     boolean keepGoing = request.getViewOptions().keepGoing;
 
     Path actionOutputRoot = env.getActionConsoleOutputDirectory();