t8y2/dbx · error · ValueError

BENCH_CANDIDATES selected no candidates

Error message

BENCH_CANDIDATES selected no candidates

What it means

configured_candidates builds the list of agent candidates from BENCH_CANDIDATES selections; if no known candidate is selected or the resulting list is empty, it raises ValueError('BENCH_CANDIDATES selected no candidates'). The bench cannot run without at least one agent.

Source

Thrown at agents/drivers/cassandra-go/bench/agent_compare.py:178

        "results": results,
    }
    json.dump(output, sys.stdout, ensure_ascii=False, indent=2)
    sys.stdout.write("\n")


def configured_candidates() -> list[Candidate]:
    selected = {item.strip() for item in env_default("BENCH_CANDIDATES", "go,jdbc").split(",") if item.strip()}
    candidates = []
    if "go" in selected:
        artifact = required_path("GO_AGENT")
        candidates.append(Candidate("go-native", [str(artifact)], artifact, os.getenv("GO_RSS_COMMAND", "")))
    if "jdbc" in selected:
        artifact = required_path("JDBC_AGENT_JAR")
        raw_command = os.getenv("JDBC_AGENT_COMMAND", "")
        command = shlex.split(raw_command) if raw_command else [env_default("JAVA_BIN", "java"), "-jar", str(artifact)]
        candidates.append(Candidate("jdbc-java", command, artifact, os.getenv("JDBC_RSS_COMMAND", "")))
    if not candidates:
        raise ValueError("BENCH_CANDIDATES selected no candidates")
    return candidates


def connection_params() -> dict:
    return {
        "host": env_default("CASSANDRA_HOST", "127.0.0.1"),
        "port": env_int("CASSANDRA_PORT", 9042),
        "database": env_default("CASSANDRA_KEYSPACE", "dbx_native_test"),
        "username": os.getenv("CASSANDRA_USERNAME", ""),
        "password": os.getenv("CASSANDRA_PASSWORD", ""),
        "url_params": os.getenv("CASSANDRA_URL_PARAMS", ""),
        "connection_string": os.getenv("CASSANDRA_CONNECTION_STRING", ""),
        "ssl": env_bool("CASSANDRA_SSL", False),
        "ca_cert_path": os.getenv("CASSANDRA_CA_CERT_PATH", ""),
        "client_cert_path": os.getenv("CASSANDRA_CLIENT_CERT_PATH", ""),
        "client_key_path": os.getenv("CASSANDRA_CLIENT_KEY_PATH", ""),
    }

View on GitHub (pinned to c0390bff16)

Solutions

1. Set BENCH_CANDIDATES to a supported name, e.g. export BENCH_CANDIDATES=jdbc
2. Check spelling against the supported selection tokens in configured_candidates
3. Verify the variable is actually exported in your shell/CI environment

Example fix

// before
BENCH_CANDIDATES= python agent_compare.py
// after
BENCH_CANDIDATES=jdbc python agent_compare.py

raw = os.getenv("BENCH_CANDIDATES", "")
selected = {token.strip() for token in raw.split(",") if token.strip()}
if not selected:
    raise SystemExit("BENCH_CANDIDATES must name at least one supported candidate (e.g. jdbc)")
print(f"candidates selected: {sorted(selected)}")

try:
    candidates = configured_candidates()
except ValueError as exc:
    if "selected no candidates" in str(exc):
        sys.exit("set BENCH_CANDIDATES, e.g. export BENCH_CANDIDATES=jdbc")
    raise

When it happens

Trigger: BENCH_CANDIDATES is empty/unset, contains only unrecognized tokens (not e.g. 'jdbc'), or every selected branch fails to append a candidate.

Common situations: Forgot to set BENCH_CANDIDATES in CI; typo like 'jdbc ' with different casing or an unsupported name; variable exported as blank in a pipeline.

Understand the failure class

Background: "environment variable is not set" and "Missing keys in environment" errors: what missing required env var messages mean and how to fix them — this error's family across 28 libraries.

Related errors

• {name} must be positive
• {name} must be positive
• {name} must contain positive integers
• {name} must be a boolean
• {name} must be a boolean

AI-assisted analysis of t8y2/dbx@c0390bff16 (2026-09-05). Data as JSON: /api/errors/f7343b1f843f5be6. Report an issue: GitHub.