diff options
Diffstat (limited to 'synapse/metrics/jemalloc.py')
| -rw-r--r-- | synapse/metrics/jemalloc.py | 114 |
1 files changed, 73 insertions, 41 deletions
diff --git a/synapse/metrics/jemalloc.py b/synapse/metrics/jemalloc.py index 6bc329f04a..1fc8a0e888 100644 --- a/synapse/metrics/jemalloc.py +++ b/synapse/metrics/jemalloc.py @@ -18,6 +18,7 @@ import os import re from typing import Iterable, Optional, overload +import attr from prometheus_client import REGISTRY, Metric from typing_extensions import Literal @@ -27,52 +28,24 @@ from synapse.metrics._types import Collector logger = logging.getLogger(__name__) -def _setup_jemalloc_stats() -> None: - """Checks to see if jemalloc is loaded, and hooks up a collector to record - statistics exposed by jemalloc. - """ - - # Try to find the loaded jemalloc shared library, if any. We need to - # introspect into what is loaded, rather than loading whatever is on the - # path, as if we load a *different* jemalloc version things will seg fault. - - # We look in `/proc/self/maps`, which only exists on linux. - if not os.path.exists("/proc/self/maps"): - logger.debug("Not looking for jemalloc as no /proc/self/maps exist") - return - - # We're looking for a path at the end of the line that includes - # "libjemalloc". - regex = re.compile(r"/\S+/libjemalloc.*$") - - jemalloc_path = None - with open("/proc/self/maps") as f: - for line in f: - match = regex.search(line.strip()) - if match: - jemalloc_path = match.group() - - if not jemalloc_path: - # No loaded jemalloc was found. - logger.debug("jemalloc not found") - return - - logger.debug("Found jemalloc at %s", jemalloc_path) - - jemalloc = ctypes.CDLL(jemalloc_path) +@attr.s(slots=True, frozen=True, auto_attribs=True) +class JemallocStats: + jemalloc: ctypes.CDLL @overload def _mallctl( - name: str, read: Literal[True] = True, write: Optional[int] = None + self, name: str, read: Literal[True] = True, write: Optional[int] = None ) -> int: ... @overload - def _mallctl(name: str, read: Literal[False], write: Optional[int] = None) -> None: + def _mallctl( + self, name: str, read: Literal[False], write: Optional[int] = None + ) -> None: ... def _mallctl( - name: str, read: bool = True, write: Optional[int] = None + self, name: str, read: bool = True, write: Optional[int] = None ) -> Optional[int]: """Wrapper around `mallctl` for reading and writing integers to jemalloc. @@ -120,7 +93,7 @@ def _setup_jemalloc_stats() -> None: # Where oldp/oldlenp is a buffer where the old value will be written to # (if not null), and newp/newlen is the buffer with the new value to set # (if not null). Note that they're all references *except* newlen. - result = jemalloc.mallctl( + result = self.jemalloc.mallctl( name.encode("ascii"), input_var_ref, input_len_ref, @@ -136,21 +109,80 @@ def _setup_jemalloc_stats() -> None: return input_var.value - def _jemalloc_refresh_stats() -> None: + def refresh_stats(self) -> None: """Request that jemalloc updates its internal statistics. This needs to be called before querying for stats, otherwise it will return stale values. """ try: - _mallctl("epoch", read=False, write=1) + self._mallctl("epoch", read=False, write=1) except Exception as e: logger.warning("Failed to reload jemalloc stats: %s", e) + def get_stat(self, name: str) -> int: + """Request the stat of the given name at the time of the last + `refresh_stats` call. This may throw if we fail to read + the stat. + """ + return self._mallctl(f"stats.{name}") + + +_JEMALLOC_STATS: Optional[JemallocStats] = None + + +def get_jemalloc_stats() -> Optional[JemallocStats]: + """Returns an interface to jemalloc, if it is being used. + + Note that this will always return None until `setup_jemalloc_stats` has been + called. + """ + return _JEMALLOC_STATS + + +def _setup_jemalloc_stats() -> None: + """Checks to see if jemalloc is loaded, and hooks up a collector to record + statistics exposed by jemalloc. + """ + + global _JEMALLOC_STATS + + # Try to find the loaded jemalloc shared library, if any. We need to + # introspect into what is loaded, rather than loading whatever is on the + # path, as if we load a *different* jemalloc version things will seg fault. + + # We look in `/proc/self/maps`, which only exists on linux. + if not os.path.exists("/proc/self/maps"): + logger.debug("Not looking for jemalloc as no /proc/self/maps exist") + return + + # We're looking for a path at the end of the line that includes + # "libjemalloc". + regex = re.compile(r"/\S+/libjemalloc.*$") + + jemalloc_path = None + with open("/proc/self/maps") as f: + for line in f: + match = regex.search(line.strip()) + if match: + jemalloc_path = match.group() + + if not jemalloc_path: + # No loaded jemalloc was found. + logger.debug("jemalloc not found") + return + + logger.debug("Found jemalloc at %s", jemalloc_path) + + jemalloc_dll = ctypes.CDLL(jemalloc_path) + + stats = JemallocStats(jemalloc_dll) + _JEMALLOC_STATS = stats + class JemallocCollector(Collector): """Metrics for internal jemalloc stats.""" def collect(self) -> Iterable[Metric]: - _jemalloc_refresh_stats() + stats.refresh_stats() g = GaugeMetricFamily( "jemalloc_stats_app_memory_bytes", @@ -184,7 +216,7 @@ def _setup_jemalloc_stats() -> None: "metadata", ): try: - value = _mallctl(f"stats.{t}") + value = stats.get_stat(t) except Exception as e: # There was an error fetching the value, skip. logger.warning("Failed to read jemalloc stats.%s: %s", t, e) |