fix: improve tracing feature #3688
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,204 @@ | ||
| // Licensed to the Apache Software Foundation (ASF) under one | ||
| // or more contributor license agreements. See the NOTICE file | ||
| // distributed with this work for additional information | ||
| // regarding copyright ownership. The ASF licenses this file | ||
| // to you under the Apache License, Version 2.0 (the | ||
| // "License"); you may not use this file except in compliance | ||
| // with the License. You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, | ||
| // software distributed under the License is distributed on an | ||
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY | ||
| // KIND, either express or implied. See the License for the | ||
| // specific language governing permissions and limitations | ||
| // under the License. | ||
|
|
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| //! Analyzes a Comet chrome trace event log (`comet-event-trace.json`) and | ||
| //! compares jemalloc usage against the sum of per-thread Comet memory pool | ||
| //! reservations. Reports any points where jemalloc exceeds the total pool size. | ||
| //! | ||
| //! Usage: | ||
| //! cargo run --bin analyze_trace -- <path-to-comet-event-trace.json> | ||
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|
||
| use serde::Deserialize; | ||
| use std::collections::HashMap; | ||
| use std::io::{BufRead, BufReader}; | ||
| use std::{env, fs::File}; | ||
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||
| /// A single Chrome trace event (only the fields we care about). | ||
| #[derive(Deserialize)] | ||
| struct TraceEvent { | ||
| name: String, | ||
| ph: String, | ||
| #[allow(dead_code)] | ||
| tid: u64, | ||
| ts: u64, | ||
| #[serde(default)] | ||
| args: HashMap<String, serde_json::Value>, | ||
| } | ||
|
|
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| /// Snapshot of memory state at a given timestamp. | ||
| struct MemorySnapshot { | ||
| ts: u64, | ||
| jemalloc: u64, | ||
| pool_total: u64, | ||
| } | ||
|
|
||
| fn format_bytes(bytes: u64) -> String { | ||
| const MB: f64 = 1024.0 * 1024.0; | ||
| format!("{:.1} MB", bytes as f64 / MB) | ||
| } | ||
|
|
||
| fn main() { | ||
| let args: Vec<String> = env::args().collect(); | ||
| if args.len() != 2 { | ||
| eprintln!("Usage: analyze_trace <path-to-comet-event-trace.json>"); | ||
| std::process::exit(1); | ||
| } | ||
|
|
||
| let file = File::open(&args[1]).expect("Failed to open trace file"); | ||
| let reader = BufReader::new(file); | ||
|
|
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| // Latest jemalloc value (global, not per-thread) | ||
| let mut latest_jemalloc: u64 = 0; | ||
| // Per-thread pool reservations: thread_NNN -> bytes | ||
| let mut pool_by_thread: HashMap<String, u64> = HashMap::new(); | ||
| // Points where jemalloc exceeded pool total | ||
| let mut violations: Vec<MemorySnapshot> = Vec::new(); | ||
| // Track peak values | ||
| let mut peak_jemalloc: u64 = 0; | ||
| let mut peak_pool_total: u64 = 0; | ||
| let mut peak_excess: u64 = 0; | ||
| let mut counter_events: u64 = 0; | ||
|
|
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| // Each line is one JSON event, possibly with a trailing comma. | ||
| // The file starts with "[ " on the first event line or as a prefix. | ||
| for line in reader.lines() { | ||
| let line = line.expect("Failed to read line"); | ||
| let trimmed = line.trim(); | ||
|
|
||
| // Skip empty lines or bare array brackets | ||
| if trimmed.is_empty() || trimmed == "[" || trimmed == "]" { | ||
| continue; | ||
| } | ||
|
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| // Strip leading "[ " (first event) and trailing comma | ||
| let json_str = trimmed | ||
| .trim_start_matches("[ ") | ||
| .trim_start_matches('[') | ||
| .trim_end_matches(','); | ||
|
|
||
| if json_str.is_empty() { | ||
| continue; | ||
| } | ||
|
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| // Only parse counter events (they contain "\"ph\": \"C\"") | ||
| if !json_str.contains("\"ph\": \"C\"") { | ||
| continue; | ||
| } | ||
|
|
||
| let event: TraceEvent = match serde_json::from_str(json_str) { | ||
| Ok(e) => e, | ||
| Err(_) => continue, | ||
| }; | ||
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| if event.ph != "C" { | ||
| continue; | ||
| } | ||
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| counter_events += 1; | ||
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| if event.name == "jemalloc_allocated" { | ||
| if let Some(val) = event.args.get("jemalloc_allocated") { | ||
| latest_jemalloc = val.as_u64().unwrap_or(0); | ||
| if latest_jemalloc > peak_jemalloc { | ||
| peak_jemalloc = latest_jemalloc; | ||
| } | ||
| } | ||
| } else if event.name.contains("comet_memory_reserved") { | ||
| // Name format: thread_NNN_comet_memory_reserved | ||
| let thread_key = event.name.clone(); | ||
| if let Some(val) = event.args.get(&event.name) { | ||
| let bytes = val.as_u64().unwrap_or(0); | ||
| pool_by_thread.insert(thread_key, bytes); | ||
| } | ||
| } else { | ||
| // Skip jvm_heap_used and other counters | ||
| continue; | ||
| } | ||
|
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||
| // After each jemalloc or pool update, check the current state | ||
| let pool_total: u64 = pool_by_thread.values().sum(); | ||
| if pool_total > peak_pool_total { | ||
| peak_pool_total = pool_total; | ||
| } | ||
|
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| if latest_jemalloc > 0 && pool_total > 0 && latest_jemalloc > pool_total { | ||
| let excess = latest_jemalloc - pool_total; | ||
| if excess > peak_excess { | ||
| peak_excess = excess; | ||
| } | ||
| // Record violation (sample - don't record every single one) | ||
| if violations.is_empty() | ||
| || event.ts.saturating_sub(violations.last().unwrap().ts) > 1_000_000 | ||
| || excess == peak_excess | ||
| { | ||
| violations.push(MemorySnapshot { | ||
| ts: event.ts, | ||
| jemalloc: latest_jemalloc, | ||
| pool_total, | ||
| }); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // Print summary | ||
| println!("=== Comet Trace Memory Analysis ===\n"); | ||
| println!("Counter events parsed: {counter_events}"); | ||
| println!("Threads with memory pools: {}", pool_by_thread.len()); | ||
| println!("Peak jemalloc allocated: {}", format_bytes(peak_jemalloc)); | ||
| println!( | ||
| "Peak pool total: {}", | ||
| format_bytes(peak_pool_total) | ||
| ); | ||
| println!( | ||
| "Peak excess (jemalloc - pool): {}", | ||
| format_bytes(peak_excess) | ||
| ); | ||
| println!(); | ||
|
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||
| if violations.is_empty() { | ||
| println!("OK: jemalloc never exceeded the total pool reservation."); | ||
| } else { | ||
| println!( | ||
| "WARNING: jemalloc exceeded pool reservation at {} sampled points:\n", | ||
| violations.len() | ||
| ); | ||
| println!( | ||
| "{:>14} {:>14} {:>14} {:>14}", | ||
| "Time (us)", "jemalloc", "pool_total", "excess" | ||
| ); | ||
| println!("{}", "-".repeat(62)); | ||
| for snap in &violations { | ||
| let excess = snap.jemalloc - snap.pool_total; | ||
| println!( | ||
| "{:>14} {:>14} {:>14} {:>14}", | ||
| snap.ts, | ||
| format_bytes(snap.jemalloc), | ||
| format_bytes(snap.pool_total), | ||
| format_bytes(excess), | ||
| ); | ||
| } | ||
| } | ||
|
|
||
| // Show final per-thread pool state | ||
| println!("\n--- Final per-thread pool reservations ---\n"); | ||
| let mut threads: Vec<_> = pool_by_thread.iter().collect(); | ||
| threads.sort_by_key(|(k, _)| (*k).clone()); | ||
| for (thread, bytes) in &threads { | ||
| println!(" {thread}: {}", format_bytes(**bytes)); | ||
| } | ||
| println!("\n Total: {}", format_bytes(pool_by_thread.values().sum())); | ||
| } |
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