From 4486d18e9fde441a438fc9d345675aabb33dface Mon Sep 17 00:00:00 2001
From: maximthomas <maxim.thomas@gmail.com>
Date: Fri, 28 Aug 2026 05:27:58 +0000
Subject: [PATCH] [#903] Grant the first replay of a conflict, and bound the rest by its class
---
opendj-server-legacy/src/main/java/org/opends/server/backends/jdbc/JDBCStorage.java | 135 ++++++++++++++++++++++++++++++++++++++-------
1 files changed, 114 insertions(+), 21 deletions(-)
diff --git a/opendj-server-legacy/src/main/java/org/opends/server/backends/jdbc/JDBCStorage.java b/opendj-server-legacy/src/main/java/org/opends/server/backends/jdbc/JDBCStorage.java
index d1d8055..24c2114 100644
--- a/opendj-server-legacy/src/main/java/org/opends/server/backends/jdbc/JDBCStorage.java
+++ b/opendj-server-legacy/src/main/java/org/opends/server/backends/jdbc/JDBCStorage.java
@@ -53,15 +53,28 @@
private static final int MAX_RETRIES = 10;
/**
- * Wall-clock budget the replays of a {@link #write} may spend, in nanoseconds. It is checked between attempts,
- * so an attempt already running is never interrupted: the loop returns after at most this window plus one
- * attempt. It bounds the conflicts that are slow to report, which {@link #MAX_RETRIES} alone does not - MySQL
- * reports a lock wait timeout only after innodb_lock_wait_timeout, 50 s by default and not overridden here, so
- * ten attempts would park a worker thread for eight minutes where a single one released it after 50 s. The
- * deadlocks this retry exists for keep their full attempt budget, since every engine reports one in well under
- * a second.
+ * Wall-clock budget the replays of a {@link #write} may spend on a {@link Conflict#AFTER_LOCK_WAIT} conflict,
+ * in nanoseconds. It is checked between attempts, so an attempt already running is never interrupted, and it
+ * bounds the replays after the first, which is granted unconditionally: the loop returns after two attempts,
+ * or after this window plus one attempt, whichever comes later. It bounds what {@link #MAX_RETRIES} alone does
+ * not - MySQL reports a lock wait timeout only after innodb_lock_wait_timeout, 50 s by default and not
+ * overridden here, so ten attempts would park a worker thread for eight minutes where two release it after
+ * 100 s.
*/
- private static final long MAX_RETRY_WINDOW_NANOS = 10L * 1000L * 1000L * 1000L; //10 s
+ private static final long LOCK_WAIT_RETRY_WINDOW_NANOS = 10L * 1000L * 1000L * 1000L; //10 s
+
+ /**
+ * Wall-clock budget the replays of a {@link #write} may spend on a {@link Conflict#PROMPT} conflict, in
+ * nanoseconds. Wider, because an attempt ending in a deadlock is not short either, for a reason of its own:
+ * detection is prompt, but the victim is charged the lock wait that precedes it, and SQL Server, Oracle and
+ * PostgreSQL all leave that wait unbounded - a victim of concurrent writers took some 12 s to be picked in CI,
+ * and under the window above the replays that followed the first were disarmed by a wait that belongs to the
+ * attempt rather than to them. Widening it is paid for by the caller, which holds a worker thread for up to
+ * this window plus one attempt where it held one for ten seconds plus an attempt before - six times as long in
+ * the worst case, and still preferable to failing an operation the engine asked to have rerun, with
+ * {@link #MAX_RETRIES} capping the attempts made inside it.
+ */
+ private static final long PROMPT_CONFLICT_RETRY_WINDOW_NANOS = 60L * 1000L * 1000L * 1000L; //60 s
/** Upper bound of the random delay before the second attempt, in milliseconds; it doubles with every attempt. */
private static final double BASE_SLEEP_ON_RETRY_MS = 50.0;
@@ -79,6 +92,15 @@
private static final int ORACLE_DEADLOCK_DETECTED = 60;
/**
+ * MySQL error number of a lock wait timeout, ER_LOCK_WAIT_TIMEOUT. Connector/J maps it to the same class 40
+ * state as a deadlock, so it is a conflict like any other and this number is only what tells the two apart:
+ * of every conflict handled here it is the one an engine reports late rather than promptly. It is keyed by the
+ * driver like the numbers above, since the engines collide on it - the same 1205 is the deadlock victim of
+ * SQL Server and a fatal "not a data file" on Oracle.
+ */
+ private static final int MYSQL_LOCK_WAIT_TIMEOUT = 1205;
+
+ /**
* Class 40 states that are transaction rollbacks but must not be replayed. 40003 leaves the outcome of the
* transaction unknown, so replaying an add that in fact committed would answer the client with
* "entry already exists", and 40002 is an integrity constraint violation, which a replay repeats rather than
@@ -837,11 +859,17 @@
* exactly that reason; {@link org.opends.server.backends.pdb.PDBStorage#write(WriteOperation)} already does so
* on the conflict exception of its own engine. The loop is bounded here, unlike PDBStorage: the database may be
* shared with writers outside this server, so a conflict is not guaranteed to clear and failing the operation is
- * better than never returning. It is bounded twice - by {@link #MAX_RETRIES} attempts and by the
- * {@link #MAX_RETRY_WINDOW_NANOS} wall-clock window - because an attempt is not guaranteed to be short: a
- * conflict an engine reports only after its own lock wait timeout would otherwise multiply that wait by the
- * attempt count. A conflict that slow consumes the whole window in one attempt and is not replayed, which is
- * what master did with it.
+ * better than never returning. It is bounded twice - by {@link #MAX_RETRIES} attempts and by a wall-clock
+ * window - because an attempt is not guaranteed to be short: a conflict an engine reports only after its own
+ * lock wait timeout would otherwise multiply that wait by the attempt count. The window is the one the class
+ * of the conflict is given - {@link #LOCK_WAIT_RETRY_WINDOW_NANOS} or
+ * {@link #PROMPT_CONFLICT_RETRY_WINDOW_NANOS} - because a window shorter than the wait that precedes a conflict
+ * does not bound that wait but only leaves the operation with no replay at all; see
+ * {@link #replayable(int, long, Throwable, String)}. Either window is checked between attempts, so an attempt
+ * already running is never interrupted, and it bounds the replays after the first: a conflicted operation holds
+ * its caller for two attempts, or for the window of its class plus one attempt, whichever is later - a minute
+ * plus an attempt for a deadlock, and for a MySQL lock wait timeout the two waits of 50 s the engine takes to
+ * report it twice.
* <p>
* Only the operation itself is replayed: a failure of {@link #getConnection()} or of the implicit
* {@link Connection#close()} - which returns the connection to the pool after a rollback - leaves the loop, so
@@ -849,7 +877,7 @@
*/
@Override
public void write(WriteOperation writeOperation) throws Exception {
- final long giveUpAt=System.nanoTime()+MAX_RETRY_WINDOW_NANOS;
+ final long startedAt=System.nanoTime();
for (int attempt=1;;attempt++) {
Exception failure=null;
String driver=null;
@@ -879,8 +907,8 @@
throw e;
}
}
- //System.nanoTime()-giveUpAt is the overflow safe form of the comparison
- if (attempt>=MAX_RETRIES || System.nanoTime()-giveUpAt>=0 || !isRetryableConflict(failure,driver)) {
+ //System.nanoTime()-startedAt is the overflow safe form of the elapsed time
+ if (!replayable(attempt, System.nanoTime()-startedAt, failure, driver)) {
throw failure;
}
//logged rather than silently absorbed, so that a deployment retrying most of its writes stays observable;
@@ -924,16 +952,81 @@
* no replay can resolve, while 1205 is exactly the deadlock victim of SQL Server. The SQL Server number is
* matched beyond its class 40 state because a deployment may add {@code xopenStates=true} to its connection
* URL, which reports the same deadlock as 42000. MySQL needs no number of its own, since its driver has already
- * mapped both conditions into class 40; see {@link #NON_REPLAYABLE_ROLLBACK_STATES} for the two class 40 states
- * that are excluded from that match.
+ * mapped both conditions into class 40 - its number is read by {@link #conflictOf} alone, and only to tell the
+ * two apart; see {@link #NON_REPLAYABLE_ROLLBACK_STATES} for the two class 40 states that are excluded from
+ * that match.
*/
static boolean isRetryableConflict(Throwable t, String driver) {
+ return conflictOf(t, driver)!=Conflict.NONE;
+ }
+
+ /**
+ * The class of a failure. Whether it is a conflict at all is what decides that the operation is replayed;
+ * which of the two remaining classes it is decides only how long the replays may go on for, since the wait an
+ * engine spends before reporting a conflict is charged to the attempt that hit it.
+ */
+ enum Conflict {
+ /** Not a conflict: no replay resolves it. */
+ NONE,
+ /** A conflict reported as soon as the engine detects it, however long the attempt waited to reach it. */
+ PROMPT,
+ /** A conflict an engine reports only once a lock wait timeout of its own has elapsed. */
+ AFTER_LOCK_WAIT
+ }
+
+ /**
+ * Returns the class of the first conflict of the given cause chain, walked as
+ * {@link #isRetryableConflict(Throwable, String)} describes, or {@link Conflict#NONE} if it carries none.
+ */
+ static Conflict conflictOf(Throwable t, String driver) {
for (int hop=0; t!=null && hop<MAX_CAUSE_HOPS; t=t.getCause(), hop++) {
- if (t instanceof SQLException && isConflict((SQLException) t, driver)) {
- return true;
+ if (t instanceof SQLException) {
+ final Conflict conflict=classOf((SQLException) t, driver);
+ if (conflict!=Conflict.NONE) {
+ return conflict;
+ }
}
}
- return false;
+ return Conflict.NONE;
+ }
+
+ /**
+ * Returns the class of a single failure. The vendor number only refines a failure {@link #isConflict} has
+ * already matched and never widens that match, which the engines colliding on 1205 do not allow: the number is
+ * read here to tell the late conflict of MySQL from the deadlock its driver reports under the same state.
+ */
+ private static Conflict classOf(SQLException e, String driver) {
+ if (!isConflict(e, driver)) {
+ return Conflict.NONE;
+ }
+ return String.valueOf(driver).contains("mysql") && e.getErrorCode()==MYSQL_LOCK_WAIT_TIMEOUT
+ ? Conflict.AFTER_LOCK_WAIT : Conflict.PROMPT;
+ }
+
+ /**
+ * Returns whether the failure of the given attempt is replayed: the decision {@link #write} takes after every
+ * attempt, made here apart from the clock so that it can be tested without a database. The first replay of a
+ * conflict is never denied, because the wait an engine spends before reporting one is charged to the attempt
+ * that hit it and is unbounded on three of the four engines here, so there is no window that some wait does not
+ * outlast; bounding that wait itself would take a session lock timeout on the transaction connection. The
+ * replays after it are bounded by the window of the class of the conflict, against the time elapsed since the
+ * first attempt began.
+ */
+ static boolean replayable(int attempt, long elapsedNanos, Throwable failure, String driver) {
+ final Conflict conflict=conflictOf(failure, driver);
+ if (conflict==Conflict.NONE || attempt>=MAX_RETRIES) {
+ return false;
+ }
+ //the engine asked for the transaction to be rerun: no clock denies that first rerun
+ if (attempt==1) {
+ return true;
+ }
+ return elapsedNanos<windowOf(conflict);
+ }
+
+ /** Returns the window the replays of the given conflict are bounded by; {@link Conflict#NONE} never gets here. */
+ private static long windowOf(Conflict conflict) {
+ return conflict==Conflict.AFTER_LOCK_WAIT ? LOCK_WAIT_RETRY_WINDOW_NANOS : PROMPT_CONFLICT_RETRY_WINDOW_NANOS;
}
private static boolean isConflict(SQLException e, String driver) {
--
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