influxdata/influxdb · error · HeapDumpError::ProfilingDisabled

heap profiling is disabled; restart with

Error message

heap profiling is disabled; restart with {MALLOC_CONF_ENV}=prof:true to enable

What it means

HeapDumpError::ProfilingDisabled is returned by dump_heap_profile when jemalloc's heap profiling feature (prof) is not active in the running process. The crate requires the process to have been started with the MALLOC_CONF environment containing prof:true; without it jemalloc cannot produce heap_v2 profile dumps. This is a configuration/runtime-startup condition, not a runtime fault.

Solutions

1. Restart the process with MALLOC_CONF=prof:true (combined with any other needed options) as the error message instructs
2. Verify with `MALLOC_CONF=print:true` or by checking the endpoint that profiling is enabled after restart
3. If profiling is too costly in prod, keep it enabled only in staging/debug deployments

Example fix

// before
./myapp
// after
MALLOC_CONF=prof:true ./myapp

fn profiling_enabled() -> bool {
    std::env::var("MALLOC_CONF").map(|v| v.split(',').any(|o| o == "prof:true")).unwrap_or(false)
}
if !profiling_enabled() { return Err("start with MALLOC_CONF=prof:true"); }

match dump_heap_profile().await {
    Err(HeapDumpError::ProfilingDisabled) => HttpResponse::new(StatusCode::PRECONDITION_FAILED, "enable MALLOC_CONF=prof:true"),
    other => other?,
}

When it happens

Trigger: Calling dump_heap_profile() (or hitting the pprof heap endpoint) in a process launched without MALLOC_CONF=prof:true — for example a service started with default env or a MALLOC_CONF that lacks the prof option.

Common situations: Deploying the binary without the jemalloc profiling env var; enabling the pprof HTTP endpoint but forgetting the restart flag; MALLOC_CONF overwritten by another profiling config (e.g. only abort_conf or background_thread set).

Related errors

• jemalloc prof.dump failed
• tempfile path was not valid C string (non-utf8 or interior…
• An unexpected error occurred in the client library
• blocking task join
• Cannot parse object store config

AI-assisted analysis of influxdata/influxdb@06200ef96b (2026-09-19). Data as JSON: /api/errors/eca174f089047e35. Report an issue: GitHub.

Appendix: source

Thrown at core/jemalloc_stats/src/lib.rs:94

/// in a user-facing message differs by build target.
pub const MALLOC_CONF_ENV: &str = if cfg!(any(
    target_os = "macos",
    target_os = "ios",
    target_os = "android",
    target_os = "dragonfly",
    target_env = "musl",
)) {
    "_RJEM_MALLOC_CONF"
} else {
    "MALLOC_CONF"
};

/// Errors returned by [`dump_heap_profile`].
#[derive(Debug, thiserror::Error)]
pub enum HeapDumpError {
    #[error("tempfile path was not valid C string (non-utf8 or interior NUL)")]
    BadTempPath,
    #[error("heap profiling is disabled; restart with {MALLOC_CONF_ENV}=prof:true to enable")]
    ProfilingDisabled,
    #[error("jemalloc prof.dump failed: {0}")]
    Jemalloc(#[from] tikv_jemalloc_ctl::Error),
    #[error("tempfile i/o: {0}")]
    Io(#[from] std::io::Error),
    #[error("blocking task join: {0}")]
    Join(#[from] tokio::task::JoinError),
}

/// Trigger a jemalloc heap profile dump and return a streaming reader for
/// the resulting `heap_v2` bytes.
///
/// Requires jemalloc built with `--enable-prof` (i.e. `tikv-jemallocator`
/// `profiling` feature) AND the binary started with `prof:true` in the
/// platform-appropriate `MALLOC_CONF` env var (or via a baked-in
/// `malloc_conf` static — see [`DEFAULT_MALLOC_CONF`]). When profiling is
/// disabled at startup this returns [`HeapDumpError::ProfilingDisabled`].
///

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