diff --git a/Cargo.lock b/Cargo.lock
index 996c782..f40b62e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4,9 +4,9 @@ version = 3
 
 [[package]]
 name = "aho-corasick"
-version = "1.0.4"
+version = "1.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6748e8def348ed4d14996fa801f4122cd763fff530258cdc03f64b25f89d3a5a"
+checksum = "b2969dcb958b36655471fc61f7e416fa76033bdd4bfed0678d8fee1e2d07a1f0"
 dependencies = [
  "memchr",
 ]
@@ -17,15 +17,6 @@ version = "2.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b4682ae6287fcf752ecaabbfcc7b6f9b72aa33933dc23a554d853aea8eea8635"
 
-[[package]]
-name = "cc"
-version = "1.0.83"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f1174fb0b6ec23863f8b971027804a42614e347eafb0a95bf0b12cdae21fc4d0"
-dependencies = [
- "libc",
-]
-
 [[package]]
 name = "env_logger"
 version = "0.10.0"
@@ -41,30 +32,19 @@ dependencies = [
 
 [[package]]
 name = "errno"
-version = "0.3.2"
+version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6b30f669a7961ef1631673d2766cc92f52d64f7ef354d4fe0ddfd30ed52f0f4f"
+checksum = "ac3e13f66a2f95e32a39eaa81f6b95d42878ca0e1db0c7543723dfe12557e860"
 dependencies = [
- "errno-dragonfly",
  "libc",
  "windows-sys",
 ]
 
-[[package]]
-name = "errno-dragonfly"
-version = "0.1.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "aa68f1b12764fab894d2755d2518754e71b4fd80ecfb822714a1206c2aab39bf"
-dependencies = [
- "cc",
- "libc",
-]
-
 [[package]]
 name = "hermit-abi"
-version = "0.3.2"
+version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "443144c8cdadd93ebf52ddb4056d257f5b52c04d3c804e657d19eb73fc33668b"
+checksum = "d77f7ec81a6d05a3abb01ab6eb7590f6083d08449fe5a1c8b1e620283546ccb7"
 
 [[package]]
 name = "humantime"
@@ -85,15 +65,15 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.147"
+version = "0.2.149"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b4668fb0ea861c1df094127ac5f1da3409a82116a4ba74fca2e58ef927159bb3"
+checksum = "a08173bc88b7955d1b3145aa561539096c421ac8debde8cbc3612ec635fee29b"
 
 [[package]]
 name = "linux-raw-sys"
-version = "0.4.5"
+version = "0.4.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "57bcfdad1b858c2db7c38303a6d2ad4dfaf5eb53dfeb0910128b2c26d6158503"
+checksum = "da2479e8c062e40bf0066ffa0bc823de0a9368974af99c9f6df941d2c231e03f"
 
 [[package]]
 name = "log"
@@ -103,7 +83,7 @@ checksum = "b5e6163cb8c49088c2c36f57875e58ccd8c87c7427f7fbd50ea6710b2f3f2e8f"
 
 [[package]]
 name = "log-instrument"
-version = "0.1.4"
+version = "0.2.0"
 dependencies = [
  "env_logger",
  "log",
@@ -121,15 +101,15 @@ dependencies = [
 
 [[package]]
 name = "memchr"
-version = "2.5.0"
+version = "2.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
+checksum = "f665ee40bc4a3c5590afb1e9677db74a508659dfd71e126420da8274909a0167"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.66"
+version = "1.0.69"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "18fb31db3f9bddb2ea821cde30a9f70117e3f119938b5ee630b7403aa6e2ead9"
+checksum = "134c189feb4956b20f6f547d2cf727d4c0fe06722b20a0eec87ed445a97f92da"
 dependencies = [
  "unicode-ident",
 ]
@@ -145,9 +125,9 @@ dependencies = [
 
 [[package]]
 name = "regex"
-version = "1.9.3"
+version = "1.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "81bc1d4caf89fac26a70747fe603c130093b53c773888797a6329091246d651a"
+checksum = "d119d7c7ca818f8a53c300863d4f87566aac09943aef5b355bb83969dae75d87"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -157,9 +137,9 @@ dependencies = [
 
 [[package]]
 name = "regex-automata"
-version = "0.3.6"
+version = "0.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fed1ceff11a1dddaee50c9dc8e4938bd106e9d89ae372f192311e7da498e3b69"
+checksum = "465c6fc0621e4abc4187a2bda0937bfd4f722c2730b29562e19689ea796c9a4b"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -168,15 +148,15 @@ dependencies = [
 
 [[package]]
 name = "regex-syntax"
-version = "0.7.4"
+version = "0.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e5ea92a5b6195c6ef2a0295ea818b312502c6fc94dde986c5553242e18fd4ce2"
+checksum = "56d84fdd47036b038fc80dd333d10b6aab10d5d31f4a366e20014def75328d33"
 
 [[package]]
 name = "rustix"
-version = "0.38.8"
+version = "0.38.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "19ed4fa021d81c8392ce04db050a3da9a60299050b7ae1cf482d862b54a7218f"
+checksum = "5a74ee2d7c2581cd139b42447d7d9389b889bdaad3a73f1ebb16f2a3237bb19c"
 dependencies = [
  "bitflags",
  "errno",
@@ -187,9 +167,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.29"
+version = "2.0.38"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c324c494eba9d92503e6f1ef2e6df781e78f6a7705a0202d9801b198807d518a"
+checksum = "e96b79aaa137db8f61e26363a0c9b47d8b4ec75da28b7d1d614c2303e232408b"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -198,18 +178,18 @@ dependencies = [
 
 [[package]]
 name = "termcolor"
-version = "1.2.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "be55cf8942feac5c765c2c993422806843c9a9a45d4d5c407ad6dd2ea95eb9b6"
+checksum = "6093bad37da69aab9d123a8091e4be0aa4a03e4d601ec641c327398315f62b64"
 dependencies = [
  "winapi-util",
 ]
 
 [[package]]
 name = "unicode-ident"
-version = "1.0.11"
+version = "1.0.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "301abaae475aa91687eb82514b328ab47a211a533026cb25fc3e519b86adfc3c"
+checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"
 
 [[package]]
 name = "winapi"
@@ -229,9 +209,9 @@ checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
 
 [[package]]
 name = "winapi-util"
-version = "0.1.5"
+version = "0.1.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "70ec6ce85bb158151cae5e5c87f95a8e97d2c0c4b001223f33a334e3ce5de178"
+checksum = "f29e6f9198ba0d26b4c9f07dbe6f9ed633e1f3d5b8b414090084349e46a52596"
 dependencies = [
  "winapi",
 ]
diff --git a/README.md b/README.md
index 3a871d0..6d1037a 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,8 @@ Offers an attribute procedural macro that adds [`log::trace!`](https://docs.rs/l
 ### Example
 
 ```rust
+use log::*;
+
 fn main() {
     env_logger::builder()
         .filter_level(LevelFilter::Trace)
@@ -24,23 +26,35 @@ fn one(x: u32) -> u32 {
     if cmp {
         return 4;
     }
-    x + 3
+    two(x + 3)
+}
+#[log_instrument::instrument]
+fn two(x: u32) -> u32 {
+    let res = x % 2;
+    debug!("res: {res}");
+    res
 }
 ```
 
 Outputs:
 
 ```
-[2023-08-30T13:58:20Z TRACE log_instrument] one enter
-[2023-08-30T13:58:20Z DEBUG one] cmp: true
-[2023-08-30T13:58:20Z TRACE log_instrument] one exit
-[2023-08-30T13:58:20Z INFO  one] 4
-[2023-08-30T13:58:20Z TRACE log_instrument] one enter
-[2023-08-30T13:58:20Z DEBUG one] cmp: false
-[2023-08-30T13:58:20Z TRACE log_instrument] one exit
-[2023-08-30T13:58:20Z INFO  one] 6
-[2023-08-30T13:58:20Z TRACE log_instrument] one enter
-[2023-08-30T13:58:20Z DEBUG one] cmp: false
-[2023-08-30T13:58:20Z TRACE log_instrument] one exit
-[2023-08-30T13:58:20Z INFO  one] 7
+[2023-10-12T16:38:00Z TRACE log_instrument] ThreadId(1)>>one
+[2023-10-12T16:38:00Z DEBUG six] cmp: true
+[2023-10-12T16:38:00Z TRACE log_instrument] ThreadId(1)<<one
+[2023-10-12T16:38:00Z INFO  six] 4
+[2023-10-12T16:38:00Z TRACE log_instrument] ThreadId(1)>>one
+[2023-10-12T16:38:00Z DEBUG six] cmp: false
+[2023-10-12T16:38:00Z TRACE log_instrument] ThreadId(1)::one>>two
+[2023-10-12T16:38:00Z DEBUG six] res: 0
+[2023-10-12T16:38:00Z TRACE log_instrument] ThreadId(1)::one<<two
+[2023-10-12T16:38:00Z TRACE log_instrument] ThreadId(1)<<one
+[2023-10-12T16:38:00Z INFO  six] 0
+[2023-10-12T16:38:00Z TRACE log_instrument] ThreadId(1)>>one
+[2023-10-12T16:38:00Z DEBUG six] cmp: false
+[2023-10-12T16:38:00Z TRACE log_instrument] ThreadId(1)::one>>two
+[2023-10-12T16:38:00Z DEBUG six] res: 1
+[2023-10-12T16:38:00Z TRACE log_instrument] ThreadId(1)::one<<two
+[2023-10-12T16:38:00Z TRACE log_instrument] ThreadId(1)<<one
+[2023-10-12T16:38:00Z INFO  six] 1
 ```
diff --git a/log-instrument/examples/five.rs b/log-instrument/examples/five.rs
index 5c81ddb..5b8b6fa 100644
--- a/log-instrument/examples/five.rs
+++ b/log-instrument/examples/five.rs
@@ -2,17 +2,6 @@
 
 use log::{debug, info, warn, LevelFilter};
 
-/// Outputs:
-/// ```text
-/// [2023-08-20T22:59:16Z TRACE log_instrument] one enter
-/// [2023-08-20T22:59:16Z TRACE log_instrument] one exit
-/// [2023-08-20T22:59:16Z INFO  five] None
-/// [2023-08-20T22:59:16Z TRACE log_instrument] one enter
-/// [2023-08-20T22:59:16Z DEBUG five] ["a", "b"]
-/// [2023-08-20T22:59:16Z DEBUG five] 23
-/// [2023-08-20T22:59:16Z TRACE log_instrument] one exit
-/// [2023-08-20T22:59:16Z INFO  five] Some(["a", "b"])
-/// ```
 fn main() {
     env_logger::builder()
         .filter_level(LevelFilter::Trace)
diff --git a/log-instrument/examples/four.rs b/log-instrument/examples/four.rs
index b85c256..3b10c7c 100644
--- a/log-instrument/examples/four.rs
+++ b/log-instrument/examples/four.rs
@@ -1,15 +1,5 @@
 use log::*;
 
-/// Outputs:
-/// ```text
-/// [2023-08-20T22:22:43Z TRACE log_instrument] one enter
-/// [2023-08-20T22:22:43Z TRACE log_instrument] one exit
-/// [2023-08-20T22:22:43Z INFO  four] None
-/// [2023-08-20T22:22:43Z TRACE log_instrument] one enter
-/// [2023-08-20T22:22:43Z DEBUG four] ["a", "b"]
-/// [2023-08-20T22:22:43Z TRACE log_instrument] one exit
-/// [2023-08-20T22:22:43Z INFO  four] Some(["a", "b"])
-/// ```
 fn main() {
     env_logger::builder()
         .filter_level(LevelFilter::Trace)
diff --git a/log-instrument/examples/one.rs b/log-instrument/examples/one.rs
index 1d7457f..5ef1582 100644
--- a/log-instrument/examples/one.rs
+++ b/log-instrument/examples/one.rs
@@ -1,20 +1,5 @@
 use log::*;
 
-/// Outputs:
-/// ```text
-/// [2023-08-20T22:21:32Z TRACE log_instrument] one enter
-/// [2023-08-20T22:21:32Z DEBUG one] cmp: true
-/// [2023-08-20T22:21:32Z TRACE log_instrument] one exit
-/// [2023-08-20T22:21:32Z INFO  one] 4
-/// [2023-08-20T22:21:32Z TRACE log_instrument] one enter
-/// [2023-08-20T22:21:32Z DEBUG one] cmp: false
-/// [2023-08-20T22:21:32Z TRACE log_instrument] one exit
-/// [2023-08-20T22:21:32Z INFO  one] 6
-/// [2023-08-20T22:21:32Z TRACE log_instrument] one enter
-/// [2023-08-20T22:21:32Z DEBUG one] cmp: false
-/// [2023-08-20T22:21:32Z TRACE log_instrument] one exit
-/// [2023-08-20T22:21:32Z INFO  one] 7
-/// ```
 fn main() {
     env_logger::builder()
         .filter_level(LevelFilter::Trace)
diff --git a/log-instrument/examples/six.rs b/log-instrument/examples/six.rs
new file mode 100644
index 0000000..7232c85
--- /dev/null
+++ b/log-instrument/examples/six.rs
@@ -0,0 +1,25 @@
+use log::*;
+
+fn main() {
+    env_logger::builder()
+        .filter_level(LevelFilter::Trace)
+        .init();
+    info!("{}", one(2));
+    info!("{}", one(3));
+    info!("{}", one(4));
+}
+#[log_instrument::instrument]
+fn one(x: u32) -> u32 {
+    let cmp = x == 2;
+    debug!("cmp: {cmp}");
+    if cmp {
+        return 4;
+    }
+    two(x + 3)
+}
+#[log_instrument::instrument]
+fn two(x: u32) -> u32 {
+    let res = x % 2;
+    debug!("res: {res}");
+    res
+}
diff --git a/log-instrument/examples/three.rs b/log-instrument/examples/three.rs
index b2bb330..48e0fdd 100644
--- a/log-instrument/examples/three.rs
+++ b/log-instrument/examples/three.rs
@@ -1,15 +1,5 @@
 use log::*;
 
-/// Outputs:
-/// ```text
-/// [2023-08-20T22:22:25Z TRACE log_instrument] one enter
-/// [2023-08-20T22:22:25Z TRACE log_instrument] one exit
-/// [2023-08-20T22:22:25Z INFO  three] None
-/// [2023-08-20T22:22:25Z TRACE log_instrument] one enter
-/// [2023-08-20T22:22:25Z DEBUG three] ["a", "b"]
-/// [2023-08-20T22:22:25Z TRACE log_instrument] one exit
-/// [2023-08-20T22:22:25Z INFO  three] Some(["a", "b"])
-/// ```
 fn main() {
     env_logger::builder()
         .filter_level(LevelFilter::Trace)
diff --git a/log-instrument/examples/two.rs b/log-instrument/examples/two.rs
index 3e42c81..c6bfa88 100644
--- a/log-instrument/examples/two.rs
+++ b/log-instrument/examples/two.rs
@@ -1,15 +1,5 @@
 use log::*;
 
-/// Outputs:
-/// ```text
-/// [2023-08-20T22:21:51Z TRACE log_instrument] one enter
-/// [2023-08-20T22:21:51Z TRACE log_instrument] one exit
-/// [2023-08-20T22:21:51Z INFO  two] None
-/// [2023-08-20T22:21:51Z TRACE log_instrument] one enter
-/// [2023-08-20T22:21:51Z DEBUG two] ["a", "b"]
-/// [2023-08-20T22:21:51Z TRACE log_instrument] one exit
-/// [2023-08-20T22:21:51Z INFO  two] Some(["a", "b"]
-/// ```
 fn main() {
     env_logger::builder()
         .filter_level(LevelFilter::Trace)
diff --git a/log-instrument/src/lib.rs b/log-instrument/src/lib.rs
index 0765ab4..5c3f32d 100644
--- a/log-instrument/src/lib.rs
+++ b/log-instrument/src/lib.rs
@@ -1,14 +1,52 @@
 pub use log_instrument_macros::*;
+use std::collections::HashMap;
+use std::fmt::Write;
+use std::sync::Mutex;
+use std::sync::OnceLock;
 
-pub struct __Instrument<'a>(&'a str);
-impl<'a> __Instrument<'a> {
-    pub fn new(s: &'a str) -> __Instrument<'a> {
-        log::trace!("{s} enter");
-        __Instrument(s)
+type InnerPath = Mutex<HashMap<std::thread::ThreadId, Vec<&'static str>>>;
+static PATH: OnceLock<InnerPath> = OnceLock::new();
+fn init_path() -> InnerPath {
+    Mutex::new(HashMap::new())
+}
+
+pub struct __Instrument;
+
+impl __Instrument {
+    pub fn new(s: &'static str) -> __Instrument {
+        // Get log
+        let mut guard = PATH.get_or_init(init_path).lock().unwrap();
+        let id = std::thread::current().id();
+        let prefix = if let Some(spans) = guard.get_mut(&id) {
+            let out = spans.iter().fold(String::new(), |mut s, x| {
+                let _ = write!(s, "::{x}");
+                s
+            });
+            spans.push(s);
+            out
+        } else {
+            guard.insert(id, vec![s]);
+            String::new()
+        };
+
+        // Write log
+        log::trace!("{id:?}{prefix}>>{s}");
+
+        // Return exit struct
+        __Instrument
     }
 }
-impl<'a> std::ops::Drop for __Instrument<'a> {
+impl std::ops::Drop for __Instrument {
     fn drop(&mut self) {
-        log::trace!("{} exit", self.0);
+        // Get log
+        let mut guard = PATH.get_or_init(init_path).lock().unwrap();
+        let id = std::thread::current().id();
+        let spans = guard.get_mut(&id).unwrap();
+        let s = spans.pop().unwrap();
+        let out = spans.iter().fold(String::new(), |mut s, x| {
+            let _ = write!(s, "::{x}");
+            s
+        });
+        log::trace!("{id:?}{out}<<{s}");
     }
 }
diff --git a/log-instrument/tests/integration_tests.rs b/log-instrument/tests/integration_tests.rs
index 575fcc6..67c04f2 100644
--- a/log-instrument/tests/integration_tests.rs
+++ b/log-instrument/tests/integration_tests.rs
@@ -3,6 +3,7 @@ const TWO: &str = "../target/debug/examples/two";
 const THREE: &str = "../target/debug/examples/three";
 const FOUR: &str = "../target/debug/examples/four";
 const FIVE: &str = "../target/debug/examples/five";
+const SIX: &str = "../target/debug/examples/six";
 
 const TIMESTAMP_RANGE: std::ops::Range<usize> = 1..20;
 
@@ -28,18 +29,18 @@ fn one() {
     assert!(output.status.success());
     assert_eq!(output.stdout, b"");
     let expected_stderr = b"\
-        [2023-08-30T13:58:20Z TRACE log_instrument] one enter\n\
-        [2023-08-30T13:58:20Z DEBUG one] cmp: true\n\
-        [2023-08-30T13:58:20Z TRACE log_instrument] one exit\n\
-        [2023-08-30T13:58:20Z INFO  one] 4\n\
-        [2023-08-30T13:58:20Z TRACE log_instrument] one enter\n\
-        [2023-08-30T13:58:20Z DEBUG one] cmp: false\n\
-        [2023-08-30T13:58:20Z TRACE log_instrument] one exit\n\
-        [2023-08-30T13:58:20Z INFO  one] 6\n\
-        [2023-08-30T13:58:20Z TRACE log_instrument] one enter\n\
-        [2023-08-30T13:58:20Z DEBUG one] cmp: false\n\
-        [2023-08-30T13:58:20Z TRACE log_instrument] one exit\n\
-        [2023-08-30T13:58:20Z INFO  one] 7\n\
+        [2023-10-12T16:29:00Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:29:00Z DEBUG one] cmp: true\n\
+        [2023-10-12T16:29:00Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:29:00Z INFO  one] 4\n\
+        [2023-10-12T16:29:00Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:29:00Z DEBUG one] cmp: false\n\
+        [2023-10-12T16:29:00Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:29:00Z INFO  one] 6\n\
+        [2023-10-12T16:29:00Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:29:00Z DEBUG one] cmp: false\n\
+        [2023-10-12T16:29:00Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:29:00Z INFO  one] 7\n\
     ";
     check(&output.stderr, expected_stderr);
 }
@@ -50,13 +51,13 @@ fn two() {
     assert!(output.status.success());
     assert_eq!(output.stdout, b"");
     let expected_stderr = b"\
-        [2023-08-30T14:16:15Z TRACE log_instrument] one enter\n\
-        [2023-08-30T14:16:15Z TRACE log_instrument] one exit\n\
-        [2023-08-30T14:16:15Z INFO  two] None\n\
-        [2023-08-30T14:16:15Z TRACE log_instrument] one enter\n\
-        [2023-08-30T14:16:15Z DEBUG two] [\"a\", \"b\"]\n\
-        [2023-08-30T14:16:15Z TRACE log_instrument] one exit\n\
-        [2023-08-30T14:16:15Z INFO  two] Some([\"a\", \"b\"])\n\
+        [2023-10-12T16:29:30Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:29:30Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:29:30Z INFO  two] None\n\
+        [2023-10-12T16:29:30Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:29:30Z DEBUG two] [\"a\", \"b\"]\n\
+        [2023-10-12T16:29:30Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:29:30Z INFO  two] Some([\"a\", \"b\"])\n\
     ";
     check(&output.stderr, expected_stderr);
 }
@@ -67,13 +68,13 @@ fn three() {
     assert!(output.status.success());
     assert_eq!(output.stdout, b"");
     let expected_stderr = b"\
-        [2023-08-30T14:18:21Z TRACE log_instrument] one enter\n\
-        [2023-08-30T14:18:21Z TRACE log_instrument] one exit\n\
-        [2023-08-30T14:18:21Z INFO  three] None\n\
-        [2023-08-30T14:18:21Z TRACE log_instrument] one enter\n\
-        [2023-08-30T14:18:21Z DEBUG three] [\"a\", \"b\"]\n\
-        [2023-08-30T14:18:21Z TRACE log_instrument] one exit\n\
-        [2023-08-30T14:18:21Z INFO  three] Some([\"a\", \"b\"])\n\
+        [2023-10-12T16:30:04Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:30:04Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:30:04Z INFO  three] None\n\
+        [2023-10-12T16:30:04Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:30:04Z DEBUG three] [\"a\", \"b\"]\n\
+        [2023-10-12T16:30:04Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:30:04Z INFO  three] Some([\"a\", \"b\"])\n\
     ";
     check(&output.stderr, expected_stderr);
 }
@@ -84,13 +85,13 @@ fn four() {
     assert!(output.status.success());
     assert_eq!(output.stdout, b"");
     let expected_stderr = b"\
-        [2023-08-30T14:20:35Z TRACE log_instrument] one enter\n\
-        [2023-08-30T14:20:35Z TRACE log_instrument] one exit\n\
-        [2023-08-30T14:20:35Z INFO  four] None\n\
-        [2023-08-30T14:20:35Z TRACE log_instrument] one enter\n\
-        [2023-08-30T14:20:35Z DEBUG four] [\"a\", \"b\"]\n\
-        [2023-08-30T14:20:35Z TRACE log_instrument] one exit\n\
-        [2023-08-30T14:20:35Z INFO  four] Some([\"a\", \"b\"])\n\
+        [2023-10-12T16:30:37Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:30:37Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:30:37Z INFO  four] None\n\
+        [2023-10-12T16:30:37Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:30:37Z DEBUG four] [\"a\", \"b\"]\n\
+        [2023-10-12T16:30:37Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:30:37Z INFO  four] Some([\"a\", \"b\"])\n\
     ";
     check(&output.stderr, expected_stderr);
 }
@@ -102,14 +103,43 @@ fn five() {
     assert_eq!(output.stdout, b"");
     println!("{:?}", std::str::from_utf8(&output.stderr).unwrap());
     let expected_stderr = b"\
-        [2023-08-30T14:21:23Z TRACE log_instrument] one enter\n\
-        [2023-08-30T14:21:23Z TRACE log_instrument] one exit\n\
-        [2023-08-30T14:21:23Z INFO  five] None\n\
-        [2023-08-30T14:21:23Z TRACE log_instrument] one enter\n\
-        [2023-08-30T14:21:23Z DEBUG five] [\"a\", \"b\"]\n\
-        [2023-08-30T14:21:23Z DEBUG five] 23\n\
-        [2023-08-30T14:21:23Z TRACE log_instrument] one exit\n\
-        [2023-08-30T14:21:23Z INFO  five] Some([\"a\", \"b\"])\n\
+        [2023-10-12T16:31:12Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:31:12Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:31:12Z INFO  five] None\n\
+        [2023-10-12T16:31:12Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:31:12Z DEBUG five] [\"a\", \"b\"]\n\
+        [2023-10-12T16:31:12Z DEBUG five] 23\n\
+        [2023-10-12T16:31:12Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:31:12Z INFO  five] Some([\"a\", \"b\"])\n\
+    ";
+    check(&output.stderr, expected_stderr);
+}
+
+#[test]
+fn six() {
+    let output = std::process::Command::new(SIX).output().unwrap();
+    assert!(output.status.success());
+    assert_eq!(output.stdout, b"");
+    println!("{:?}", std::str::from_utf8(&output.stderr).unwrap());
+    let expected_stderr = b"\
+        [2023-10-12T16:31:54Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:31:54Z DEBUG six] cmp: true\n\
+        [2023-10-12T16:31:54Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:31:54Z INFO  six] 4\n\
+        [2023-10-12T16:31:54Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:31:54Z DEBUG six] cmp: false\n\
+        [2023-10-12T16:31:54Z TRACE log_instrument] ThreadId(1)::one>>two\n\
+        [2023-10-12T16:31:54Z DEBUG six] res: 0\n\
+        [2023-10-12T16:31:54Z TRACE log_instrument] ThreadId(1)::one<<two\n\
+        [2023-10-12T16:31:54Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:31:54Z INFO  six] 0\n\
+        [2023-10-12T16:31:54Z TRACE log_instrument] ThreadId(1)>>one\n\
+        [2023-10-12T16:31:54Z DEBUG six] cmp: false\n\
+        [2023-10-12T16:31:54Z TRACE log_instrument] ThreadId(1)::one>>two\n\
+        [2023-10-12T16:31:54Z DEBUG six] res: 1\n\
+        [2023-10-12T16:31:54Z TRACE log_instrument] ThreadId(1)::one<<two\n\
+        [2023-10-12T16:31:54Z TRACE log_instrument] ThreadId(1)<<one\n\
+        [2023-10-12T16:31:54Z INFO  six] 1\n\
     ";
     check(&output.stderr, expected_stderr);
 }