Linearizability checker memory reduction #40149
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The cache used in linearizability checker now uses approximately 6x less
memory by changing the cache from a set of (bits, state) tuples into a
map from bits -> { state }.
Each combination of states is kept once only, building on the
assumption that the number of state permutations is small compared to
the number of bits permutations. For those histories that are difficult
to check we will have many bits combinations that use the same state
permutations.
We end up now using approximately 15 bytes per entry compared to 101
bytes before, ie. a 6x improvement, allowing us to linearizability check
significantly longer histories.
Re-enabled linearizability checker in CoordinatorTests, hoping above
ensures we no longer un out of memory.
henningandersen
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Pinging @elastic/es-distributed |
ywelsch
approved these changes
Mar 18, 2019
server/src/test/java/org/elasticsearch/cluster/coordination/LinearizabilityChecker.java
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Linearizability cache now use indexOf/indexGet/indexReplace/indexInsert to optimize performance a bit.
henningandersen
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Mar 18, 2019
The cache used in linearizability checker now uses approximately 6x less
memory by changing the cache from a set of (bits, state) tuples into a
map from bits -> { state }.
Each combination of states is kept once only, building on the
assumption that the number of state permutations is small compared to
the number of bits permutations. For those histories that are difficult
to check we will have many bits combinations that use the same state
permutations.
We end up now using approximately 15 bytes per entry compared to 101
bytes before, ie. a 6x improvement, allowing us to linearizability check
significantly longer histories.
Re-enabled linearizability checker in CoordinatorTests, hoping above
ensures we no longer run out of memory.
Resolves #39437
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The cache used in linearizability checker now uses approximately 6x less
memory by changing the cache from a set of (bits, state) tuples into a
map from bits -> { state }.
Each combination of states is kept once only, building on the
assumption that the number of state permutations is small compared to
the number of bits permutations. For those histories that are difficult
to check we will have many bits combinations that use the same state
permutations.
We end up now using approximately 15 bytes per entry compared to 101
bytes before, ie. a 6x improvement, allowing us to linearizability check
significantly longer histories.
Re-enabled linearizability checker in CoordinatorTests, hoping above
ensures we no longer un out of memory.
Resolves #39437