theonedev/onedev · error · IllegalArgumentException

{0} flags already created

Error message

{0} flags already created

What it means

A RevWalk can create at most 32 RevFlags (one bit per flag, minus reserved bits); allocFlag() throws this IllegalArgumentException once no free bits remain. It is thrown when RevWalk.newFlag(name) is called after all flag bits have been handed out.

Source

Thrown at server-core/src/main/java/org/eclipse/jgit/revwalk/RevWalk.java:1427

	 * <p>
	 * Applications are only assured to be able to create 24 unique flags on any
	 * given revision walker instance. Any flags beyond 24 are offered only if
	 * the implementation has extra free space within its internal storage.
	 *
	 * @param name
	 *            description of the flag, primarily useful for debugging.
	 * @return newly constructed flag instance.
	 * @throws java.lang.IllegalArgumentException
	 *             too many flags have been reserved on this revision walker.
	 */
	public RevFlag newFlag(String name) {
		final int m = allocFlag();
		return new RevFlag(this, name, m);
	}

	int allocFlag() {
		if (freeFlags == 0)
			throw new IllegalArgumentException(
					MessageFormat.format(JGitText.get().flagsAlreadyCreated,
							Integer.valueOf(32 - RESERVED_FLAGS)));
		final int m = Integer.lowestOneBit(freeFlags);
		freeFlags &= ~m;
		return m;
	}

	/**
	 * Automatically carry a flag from a child commit to its parents.
	 * <p>
	 * A carried flag is copied from the child commit onto its parents when the
	 * child commit is popped from the lowest level of walk's internal graph.
	 *
	 * @param flag
	 *            the flag to carry onto parents, if set on a descendant.
	 */
	public void carry(RevFlag flag) {
		if ((freeFlags & flag.mask) != 0)

View on GitHub (pinned to d44925c47c)

Solutions

1. Reuse a fixed small set of flags instead of creating one per item or per request.
2. Call revWalk.disposeFlag(flag) when a flag is no longer needed to return its bit.
3. Create a fresh RevWalk per traversal instead of reusing one indefinitely.
4. Refactor to encode per-item state elsewhere (e.g. a map keyed by commit) rather than flags.

Example fix

// before
for (String name : names) flags.add(walk.newFlag(name)); // >32 names -> throws
// after
Map<String, RevFlag> flags = new HashMap<>();
for (String name : names) {
    if (flags.size() >= 20) throw new IllegalStateException("too many flags");
    flags.put(name, walk.newFlag(name));
}

if (flagCount >= 20) throw new IllegalStateException("RevWalk flag budget exhausted");
RevFlag f = walk.newFlag(name);

// track budget in a small wrapper
class FlagPool { int used = 0; RevFlag create(RevWalk w, String n) { if (used >= 20) throw new IllegalStateException(); used++; return w.newFlag(n); } }

try {
    flag = walk.newFlag(name);
} catch (IllegalArgumentException e) {
    throw new IllegalStateException("Too many RevFlags created (max 32)", e);
}

When it happens

Trigger: Calling revWalk.newFlag(...) more than 32-minus-reserved times on the same RevWalk instance; creating flags inside a loop that runs per item instead of once per walk; leaking flags by never disposing them (revWalk.disposeFlag) in long-lived walks.

Common situations: Long-running server walks reused across many requests that accumulate new flags; plugin/framework code generating flags per user request from a shared walk.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• Flag {0} is disposed
• Flag {0} not from this walk
• Ref name is required when commit hash is specified
• Either commit hash, branch or tag should be specified
• Unable to find commit to import build spec (import project:

AI-assisted analysis of theonedev/onedev@d44925c47c (2026-09-06). Data as JSON: /api/errors/63917a321b803a30. Report an issue: GitHub.