U_MEMORY_ALLOCATION_ERROR

U_MEMORY_ALLOCATION_ERROR

Error message

gencmn: unable to allocate memory for line buffer of size %d\n

What it means

At the very start of createCommonDataFile, gencmn allocates its line buffer with uprv_malloc(LINE_BUFFER_SIZE); a nullptr return means the host is out of memory, so it exits U_MEMORY_ALLOCATION_ERROR (pkg_gencmn.cpp:132). This is a startup OOM, before any real work.

Source

Thrown at deps/icu-small/source/tools/toolutil/pkg_gencmn.cpp:132

/* map non-tree separator (such as '\') to tree separator ('/') inplace. */
static void
fixDirToTreePath(char *s);
/* -------------------------------------------------------------------------- */

U_CAPI void U_EXPORT2
createCommonDataFile(const char *destDir, const char *name, const char *entrypointName, const char *type, const char *source, const char *copyRight,
                     const char *dataFile, uint32_t max_size, UBool sourceTOC, UBool verbose, char *gencmnFileName) {
    static char buffer[4096];
    char *line;
    char *linePtr;
    char *s = nullptr;
    UErrorCode errorCode=U_ZERO_ERROR;
    uint32_t i, fileOffset, basenameOffset, length, nread;
    FileStream *in, *file;

    line = (char *)uprv_malloc(sizeof(char) * LINE_BUFFER_SIZE);
    if (line == nullptr) {
        fprintf(stderr, "gencmn: unable to allocate memory for line buffer of size %d\n", LINE_BUFFER_SIZE);
        exit(U_MEMORY_ALLOCATION_ERROR);
    }

    linePtr = line;

    maxSize = max_size;

    if (destDir == nullptr) {
        destDir = u_getDataDirectory();
    }
    if (name == nullptr) {
        name = COMMON_DATA_NAME;
    }
    if (type == nullptr) {
        type = DATA_TYPE;
    }
    if (source == nullptr) {
        source = ".";

View on GitHub (pinned to 1b2de5e052)

Solutions

Raise available memory / virtual-memory ulimit for the build.
Reduce parallelism (e.g. make -j2) to cut peak RSS.
Add swap or run gencmn in isolation to confirm it is a host-pressure issue.

Example fix

// before
make -j$(nproc)      # OOM during gencmn
// after
( ulimit -v unlimited; make -j2 )

Defensive patterns

Strategy: retry

Validate before calling

# Refuse to start gencmn under memory pressure / low ulimit.
avail=$(awk '/MemAvailable/{print int($2/1024)}' /proc/meminfo 2>/dev/null)
[ "${avail:-999999}" -gt 128 ] || { echo "host low on memory for gencmn"; exit 2; }

Try / catch

# Retry gencmn with reduced parallelism / raised ulimit on OOM (exit 7).
for cfg in "-j$(nproc)" "-j2"; do
  ( ulimit -v unlimited; make $cfg ) && break || { [ $? -eq 7 ] || exit; }
done

Prevention

Cap build parallelism on memory-constrained hosts.
Raise virtual-memory ulimits for build processes.
Provide swap for CI runners to absorb peak RSS.

When it happens

Trigger: System is out of memory when gencmn launches, or the process virtual-memory limit (ulimit -v) is too small to satisfy even the initial line-buffer allocation.

Common situations: Memory-constrained CI containers; heavily parallel builds (make -jN) exhausting RAM; a cgroup/ulimit cap that is too low; swap disabled.

Related errors

AI-assisted analysis of nodejs/node@1b2de5e052 (2026-08-13). Data as JSON: /api/errors/f17eca13f313ad1f. Report an issue: GitHub.