From 4deb413813f619b3e859abf435b61efc09cafe09 Mon Sep 17 00:00:00 2001 From: Kevin Grittner Date: Wed, 5 Apr 2017 10:04:36 -0500 Subject: [PATCH] Add isolation test for SERIALIZABLE READ ONLY DEFERRABLE. This improves code coverage and lays a foundation for testing similar issues in a distributed environment. Author: Thomas Munro Reviewed-by: Michael Paquier --- .../expected/read-only-anomaly-2.out | 44 +++++++++++++++++++ .../expected/read-only-anomaly-3.out | 26 +++++++++++ .../isolation/expected/read-only-anomaly.out | 25 +++++++++++ src/test/isolation/isolation_schedule | 3 ++ src/test/isolation/isolationtester.c | 8 ++++ .../isolation/specs/read-only-anomaly-2.spec | 42 ++++++++++++++++++ .../isolation/specs/read-only-anomaly-3.spec | 39 ++++++++++++++++ .../isolation/specs/read-only-anomaly.spec | 38 ++++++++++++++++ 8 files changed, 225 insertions(+) create mode 100644 src/test/isolation/expected/read-only-anomaly-2.out create mode 100644 src/test/isolation/expected/read-only-anomaly-3.out create mode 100644 src/test/isolation/expected/read-only-anomaly.out create mode 100644 src/test/isolation/specs/read-only-anomaly-2.spec create mode 100644 src/test/isolation/specs/read-only-anomaly-3.spec create mode 100644 src/test/isolation/specs/read-only-anomaly.spec diff --git a/src/test/isolation/expected/read-only-anomaly-2.out b/src/test/isolation/expected/read-only-anomaly-2.out new file mode 100644 index 0000000000..f43aa6a299 --- /dev/null +++ b/src/test/isolation/expected/read-only-anomaly-2.out @@ -0,0 +1,44 @@ +Parsed test spec with 3 sessions + +starting permutation: s2rx s2ry s1ry s1wy s1c s2wx s2c s3c +step s2rx: SELECT balance FROM bank_account WHERE id = 'X'; +balance + +0 +step s2ry: SELECT balance FROM bank_account WHERE id = 'Y'; +balance + +0 +step s1ry: SELECT balance FROM bank_account WHERE id = 'Y'; +balance + +0 +step s1wy: UPDATE bank_account SET balance = 20 WHERE id = 'Y'; +step s1c: COMMIT; +step s2wx: UPDATE bank_account SET balance = -11 WHERE id = 'X'; +step s2c: COMMIT; +step s3c: COMMIT; + +starting permutation: s2rx s2ry s1ry s1wy s1c s3r s3c s2wx +step s2rx: SELECT balance FROM bank_account WHERE id = 'X'; +balance + +0 +step s2ry: SELECT balance FROM bank_account WHERE id = 'Y'; +balance + +0 +step s1ry: SELECT balance FROM bank_account WHERE id = 'Y'; +balance + +0 +step s1wy: UPDATE bank_account SET balance = 20 WHERE id = 'Y'; +step s1c: COMMIT; +step s3r: SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; +id balance + +X 0 +Y 20 +step s3c: COMMIT; +step s2wx: UPDATE bank_account SET balance = -11 WHERE id = 'X'; +ERROR: could not serialize access due to read/write dependencies among transactions diff --git a/src/test/isolation/expected/read-only-anomaly-3.out b/src/test/isolation/expected/read-only-anomaly-3.out new file mode 100644 index 0000000000..1c10ad7ebf --- /dev/null +++ b/src/test/isolation/expected/read-only-anomaly-3.out @@ -0,0 +1,26 @@ +Parsed test spec with 3 sessions + +starting permutation: s2rx s2ry s1ry s1wy s1c s3r s2wx s2c s3c +step s2rx: SELECT balance FROM bank_account WHERE id = 'X'; +balance + +0 +step s2ry: SELECT balance FROM bank_account WHERE id = 'Y'; +balance + +0 +step s1ry: SELECT balance FROM bank_account WHERE id = 'Y'; +balance + +0 +step s1wy: UPDATE bank_account SET balance = 20 WHERE id = 'Y'; +step s1c: COMMIT; +step s3r: SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; +step s2wx: UPDATE bank_account SET balance = -11 WHERE id = 'X'; +step s2c: COMMIT; +step s3r: <... completed> +id balance + +X -11 +Y 20 +step s3c: COMMIT; diff --git a/src/test/isolation/expected/read-only-anomaly.out b/src/test/isolation/expected/read-only-anomaly.out new file mode 100644 index 0000000000..d40425df28 --- /dev/null +++ b/src/test/isolation/expected/read-only-anomaly.out @@ -0,0 +1,25 @@ +Parsed test spec with 3 sessions + +starting permutation: s2rx s2ry s1ry s1wy s1c s3r s2wx s2c s3c +step s2rx: SELECT balance FROM bank_account WHERE id = 'X'; +balance + +0 +step s2ry: SELECT balance FROM bank_account WHERE id = 'Y'; +balance + +0 +step s1ry: SELECT balance FROM bank_account WHERE id = 'Y'; +balance + +0 +step s1wy: UPDATE bank_account SET balance = 20 WHERE id = 'Y'; +step s1c: COMMIT; +step s3r: SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; +id balance + +X 0 +Y 20 +step s2wx: UPDATE bank_account SET balance = -11 WHERE id = 'X'; +step s2c: COMMIT; +step s3c: COMMIT; diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 8e404b7a35..fc1918dedc 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -1,3 +1,6 @@ +test: read-only-anomaly +test: read-only-anomaly-2 +test: read-only-anomaly-3 test: read-write-unique test: read-write-unique-2 test: read-write-unique-3 diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index f77f465751..4d18710bdf 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -231,6 +231,14 @@ main(int argc, char **argv) appendPQExpBuffer(&wait_query, ",%s", backend_pids[i]); appendPQExpBufferStr(&wait_query, "}'::integer[]"); + /* Also detect certain wait events. */ + appendPQExpBufferStr(&wait_query, + " OR EXISTS (" + " SELECT * " + " FROM pg_catalog.pg_stat_activity " + " WHERE pid = $1 " + " AND wait_event IN ('SafeSnapshot'))"); + res = PQprepare(conns[0], PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) { diff --git a/src/test/isolation/specs/read-only-anomaly-2.spec b/src/test/isolation/specs/read-only-anomaly-2.spec new file mode 100644 index 0000000000..9812f49ee4 --- /dev/null +++ b/src/test/isolation/specs/read-only-anomaly-2.spec @@ -0,0 +1,42 @@ +# The example from the paper "A read-only transaction anomaly under snapshot +# isolation"[1]. +# +# Here we test that serializable snapshot isolation (SERIALIZABLE) doesn't +# suffer from the anomaly, because s2 is aborted upon detection of a cycle. +# +# [1] http://www.cs.umb.edu/~poneil/ROAnom.pdf + +setup +{ + CREATE TABLE bank_account (id TEXT PRIMARY KEY, balance DECIMAL NOT NULL); + INSERT INTO bank_account (id, balance) VALUES ('X', 0), ('Y', 0); +} + +teardown +{ + DROP TABLE bank_account; +} + +session "s1" +setup { BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; } +step "s1ry" { SELECT balance FROM bank_account WHERE id = 'Y'; } +step "s1wy" { UPDATE bank_account SET balance = 20 WHERE id = 'Y'; } +step "s1c" { COMMIT; } + +session "s2" +setup { BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; } +step "s2rx" { SELECT balance FROM bank_account WHERE id = 'X'; } +step "s2ry" { SELECT balance FROM bank_account WHERE id = 'Y'; } +step "s2wx" { UPDATE bank_account SET balance = -11 WHERE id = 'X'; } +step "s2c" { COMMIT; } + +session "s3" +setup { BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; } +step "s3r" { SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; } +step "s3c" { COMMIT; } + +# without s3, s1 and s2 commit +permutation "s2rx" "s2ry" "s1ry" "s1wy" "s1c" "s2wx" "s2c" "s3c" + +# once s3 observes the data committed by s1, a cycle is created and s2 aborts +permutation "s2rx" "s2ry" "s1ry" "s1wy" "s1c" "s3r" "s3c" "s2wx" diff --git a/src/test/isolation/specs/read-only-anomaly-3.spec b/src/test/isolation/specs/read-only-anomaly-3.spec new file mode 100644 index 0000000000..58a159a949 --- /dev/null +++ b/src/test/isolation/specs/read-only-anomaly-3.spec @@ -0,0 +1,39 @@ +# The example from the paper "A read-only transaction anomaly under snapshot +# isolation"[1]. +# +# Here we test that serializable snapshot isolation can avoid the anomaly +# without aborting any tranasctions, by instead causing s3 to be deferred +# until a safe snapshot can be taken. +# +# [1] http://www.cs.umb.edu/~poneil/ROAnom.pdf + +setup +{ + CREATE TABLE bank_account (id TEXT PRIMARY KEY, balance DECIMAL NOT NULL); + INSERT INTO bank_account (id, balance) VALUES ('X', 0), ('Y', 0); +} + +teardown +{ + DROP TABLE bank_account; +} + +session "s1" +setup { BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; } +step "s1ry" { SELECT balance FROM bank_account WHERE id = 'Y'; } +step "s1wy" { UPDATE bank_account SET balance = 20 WHERE id = 'Y'; } +step "s1c" { COMMIT; } + +session "s2" +setup { BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; } +step "s2rx" { SELECT balance FROM bank_account WHERE id = 'X'; } +step "s2ry" { SELECT balance FROM bank_account WHERE id = 'Y'; } +step "s2wx" { UPDATE bank_account SET balance = -11 WHERE id = 'X'; } +step "s2c" { COMMIT; } + +session "s3" +setup { BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE READ ONLY DEFERRABLE; } +step "s3r" { SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; } +step "s3c" { COMMIT; } + +permutation "s2rx" "s2ry" "s1ry" "s1wy" "s1c" "s3r" "s2wx" "s2c" "s3c" diff --git a/src/test/isolation/specs/read-only-anomaly.spec b/src/test/isolation/specs/read-only-anomaly.spec new file mode 100644 index 0000000000..d331e4200a --- /dev/null +++ b/src/test/isolation/specs/read-only-anomaly.spec @@ -0,0 +1,38 @@ +# The example from the paper "A read-only transaction anomaly under snapshot +# isolation"[1]. +# +# Here we use snapshot isolation (REPEATABLE READ), so that s3 sees a state of +# afairs that is not consistent with any serial ordering of s1 and s2. +# +# [1] http://www.cs.umb.edu/~poneil/ROAnom.pdf + +setup +{ + CREATE TABLE bank_account (id TEXT PRIMARY KEY, balance DECIMAL NOT NULL); + INSERT INTO bank_account (id, balance) VALUES ('X', 0), ('Y', 0); +} + +teardown +{ + DROP TABLE bank_account; +} + +session "s1" +setup { BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ; } +step "s1ry" { SELECT balance FROM bank_account WHERE id = 'Y'; } +step "s1wy" { UPDATE bank_account SET balance = 20 WHERE id = 'Y'; } +step "s1c" { COMMIT; } + +session "s2" +setup { BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ; } +step "s2rx" { SELECT balance FROM bank_account WHERE id = 'X'; } +step "s2ry" { SELECT balance FROM bank_account WHERE id = 'Y'; } +step "s2wx" { UPDATE bank_account SET balance = -11 WHERE id = 'X'; } +step "s2c" { COMMIT; } + +session "s3" +setup { BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ; } +step "s3r" { SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; } +step "s3c" { COMMIT; } + +permutation "s2rx" "s2ry" "s1ry" "s1wy" "s1c" "s3r" "s2wx" "s2c" "s3c"