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HACK: instrument page_service to count nonblocking consecutive getpage requests

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This commit is contained in:
Christian Schwarz
2024-09-11 19:25:19 +01:00
parent 7d7d1f354b
commit 02b7cdb305
2 changed files with 24 additions and 6 deletions
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10
pageserver/src/metrics.rs
View File

@@ -3170,6 +3170,16 @@ static TOKIO_EXECUTOR_THREAD_COUNT: Lazy<UIntGaugeVec> = Lazy::new(|| {
.unwrap()
});
pub(crate) static CONSECUTIVE_NONBLOCKING_GETPAGE_REQUESTS_HISTOGRAM: Lazy<Histogram> =
Lazy::new(|| {
register_histogram!(
"pageserver_consecutive_nonblocking_getpage_requests",
"Number of consecutive nonblocking getpage requests",
vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, ],
)
.unwrap()
});
pub(crate) fn set_tokio_runtime_setup(setup: &str, num_threads: NonZeroUsize) {
static SERIALIZE: std::sync::Mutex<()> = std::sync::Mutex::new(());
let _guard = SERIALIZE.lock().unwrap();

20
pageserver/src/page_service.rs
View File

@@ -43,7 +43,7 @@ use crate::basebackup;
use crate::basebackup::BasebackupError;
use crate::config::PageServerConf;
use crate::context::{DownloadBehavior, RequestContext};
use crate::metrics;
use crate::metrics::{self, CONSECUTIVE_NONBLOCKING_GETPAGE_REQUESTS_HISTOGRAM};
use crate::metrics::{ComputeCommandKind, COMPUTE_COMMANDS_COUNTERS, LIVE_CONNECTIONS};
use crate::pgdatadir_mapping::Version;
use crate::span::debug_assert_current_span_has_tenant_and_timeline_id;
@@ -577,14 +577,21 @@ impl PageServerHandler {
}
}
let mut num_consecutive_getpage_requests = 0;
loop {
// read request bytes (it's exactly 1 PagestreamFeMessage per CopyData)
let msg = tokio::select! {
biased;
_ = self.cancel.cancelled() => {
return Err(QueryError::Shutdown)
let msg = loop {
tokio::select! {
biased;
_ = self.cancel.cancelled() => {
return Err(QueryError::Shutdown)
}
msg = pgb.read_message() => { break msg; }
() = futures::future::ready(()) => {
CONSECUTIVE_NONBLOCKING_GETPAGE_REQUESTS_HISTOGRAM.observe(num_consecutive_getpage_requests as f64);
num_consecutive_getpage_requests = 0;
}
}
msg = pgb.read_message() => { msg }
};
let copy_data_bytes = match msg? {
Some(FeMessage::CopyData(bytes)) => bytes,
@@ -626,6 +633,7 @@ impl PageServerHandler {
)
}
PagestreamFeMessage::GetPage(req) => {
num_consecutive_getpage_requests += 1;
fail::fail_point!("ps::handle-pagerequest-message::getpage");
// shard_id is filled in by the handler
let span = tracing::info_span!("handle_get_page_at_lsn_request", rel = %req.rel, blkno = %req.blkno, req_lsn = %req.request_lsn);